An estimated 957,000 shoppers in the US alone ordered Apple Watches on Friday and this popularity surpassed expectations - even Apple's. In a leaked memo from the firm's Angela Ahrendts, the retail chief said that customers won't be able to buy an Apple Watch in store 'through the month of May' due to 'high global interest combined with our initial supply.' It was expected to launch on 24 April. Ms Ahrendts added it had not been an easy decision and would provide more updates as the firm gets 'closer to in-store availability.' Scroll down for video . In a leaked memo from Apple's Angela Ahrendts the retail chief wrote: 'Due to high global interest combined with our initial supply, we are only taking orders online right now [and] we expect this to continue through the month of May.' It was expected to launch on 24 April . The memo was seen by Rhiannon Williams at The Telegraph. Pre-orders of the watch began on Friday at 12.01am PDT (8.01am BST) and within an hour many models in various regions had sold out including the most expensive 38mm gold Edition version in the US and Canada. Models were showing a shipping time of four to six weeks or, in some cases, June despite the watch going on general sale on 24 April. An estimated 957,000 American shoppers ordered Apple Watches on Friday. That estimate comes from Slice Intelligence, which measures digital commerce by tracking consumer e-receipts. Its data from online shoppers showed an average of 1.3 watches bought per customer, with $503.83 (£337) spent per item - although Apple has not officially confirmed any sales figures. In a recent Goldman Sachs survey, more than 10 per cent of iPhone owners say they will buy an Apple Watch, a new survey has found. Goldmach Sachs surveyed 1,000 people, and found 11% of people who own an iPhone are 'very likely' to buy the $349 smart timepiece this year. It said the demand for the Watch was 'encouraging', and says sales are likely to hit hit traditional watch firms. It was initially believed that those who were willing to queue on 24 April would be able to buy the Watch before people who had pre-ordered. But Ms Ahrendts memo has confirmed otherwise. 'It's important to remember that Apple Watch is not just a new product but an entirely new category for us,' the memo continued. 'There's never been anything quite like it.  That's why, for the first time, we are previewing a new product in our stores before it has started shipping. 'Given the high interest and initial supply at launch, we will be able to get customers the model they want earlier and faster by taking orders online.' She added that this isn't the way Apple intends to launch all new products form now on and it loves 'those blockbuster Apple product launch days', but told store employees to be prepared for the changes. On Friday many buyers reported Apple's site was still down after the launch time, forcing them to order the device through the Apple App Store on their phones or tablets. As part of the first wave of pre-orders, the Watch can be bought online by people in the US, Canada, UK, Germany, France, Australia, Hong Kong, China and Japan. The Watch also went on display in Apple stores across these regions, as well as in Galeries Lafayette in Paris, Isetan in Tokyo, Selfridges in London, and select Apple resellers in Japan and China. Online pre-orders began on Friday at 12.01am PDT (8am BST) and although Apple said the devices will ship on 24 April within just an hour this had been pushed back to June. Buyers also reported the site was still down after the launch time, forcing them to order the device through the Apple App Store app . Ms Ahrendts added it had not been an easy decision and would provide more updates as the firm gets 'closer to in-store availability.' It was initially thought those who were willing to queue on 24 April would get the Watch in stores before people who had pre-ordered. But Ms Ahrendts' memo has confirmed otherwise . 'Will the Apple Watch change your life? Well, possibly more than many realise until they start using it. 'After a day or two with the watch, a strange thing happened - I completely stopped checking my phone. 'While Apple may be the firm that really creates phone addiction, meaning we are constantly checking our handsets, with the Apple Watch it may have cured it. 'Apple undoubtedly has another hit on its hands with the watch. 'As more and more apps appear, and developers actually get to spend time with it, I fully expect it be used in ways we can't even imagine now. 'Much like the iPhone, apps could propel this to become a new computing platform - and even with the features it already has, the Apple watch is the most elegant way to communicate digitally.' Mark Prigg in New York . As with all Apple launches, the Californian tech giant took its store offline hours before the pre-order time to update its product pages. However, shortly after the pre-orders opened customers took to Twitter to complain the site was still down and they couldn't access the checkout. One said: 'Irritated that I stayed up until 3AM to pre-order an #AppleWatch and the site was down until after the May inventory already sold out.' And even after orders had been placed, some customers had trouble receiving confirmation details and delivery dates. One Twitter user wrote: '#AppleWatch ordered but no email confirmation and the 'orders' section on their site and app is down so I can't confirm it went through.' Another wrote: 'No way in hell am I preordering an #AppleWatch today when it won't ship until June.' and another added: 'There's an #AppleWatch for everyone.' Unless you want it before June.' But for people who want to try on the Watch they can book an appointment online. A MailOnline investigation earlier this week revealed that the UK is the most expensive place in the world to buy the majority of Apple Watch models. Apple's site and app still say the Watch is available from 24 April, but when a model is selected and added to the customer's online basket (pictured), this changes. A Sport model currently has a dispatch time of four to six weeks, while the Edition model has a June delivery date . And for people who want to try on the Watch  they can book an appointment online (pictured). The memo added this isn't the way Apple intends to launch all new products form now on and it loves 'those blockbuster Apple product launch days' but told store employees to prepare for the change . The most expensive Edition model costs up to £2,500 more in the UK compared to elsewhere in the world, while at the lower end of the scale British buyers pay up to £63 more for the Sport model. The cheapest model is the 38mm Sport version and costs £299 in the UK. In the US, the same model costs $349, but this doesn't include sales tax. Sales tax in the US depends on the region where the product is sold, but as an example California has one of the highest rates - at 9% - while Montana has zero. All prices shown in the table above are for the most expensive option in each model and region. Prices also include all relevant sales taxes. Beneath each foreign price is the conversion rate in GBP. In the US, California was chosen because it has one of the highest sales taxes at 9%, while Montana was chosen for the opposite end of the scale because it doesn't have a sales tax. Quebec in Canada has one of the highest sales taxes at 15%, while Alberta has one of the lowest at 5%. Prices and conversions were correct at the time of writing. With both of these sales taxes added to the price of the Sports model in the US, the total cost works out at $380.41 (£257) and $349 (£236) in the respective states. This is a difference of £42 when bought in California, compared to the UK, and £63 when compared to Montana. The effect is magnified for the top-of-the-range Edition version, which costs from £8,000 for the 38mm model in Britain, compared to a starting price of $10,000 in the US. At the time of writing, $10,000 converts to £6,769 - which equates to a difference of £1,231 before charges are taken into account. The most expensive version of the 38mm edition in the UK is £13,500 in the UK, and $17,000 in the US. When sales taxes are added to the US model, the price rises to $18,530 in California, which converts to £12,543 - a difference of £957.
The leaked memo was written by Apple's retail chief Angela Ahrendts . She said she expects online orders 'to continue through the month of May' And added it had not been an easy decision and would provide more updates as the firm gets 'closer to in-store availability'