Making Mayo by hand , using whisk , emulsion breaks down I'm trying to make homemade mayonaise and it's not really working out well.

I got a glass bowl that's fairly deep and use the following ingredients:

*  1 egg yolk*
* 1/2 teaspoon salt (not kosher)
* 1/2 teaspoon dry mustard
* 2 pinches sugar 
* 2 teaspoons fresh squeezed lemon juice
* 1 tablespoon white wine vinegar
* 1 cup oil 


I put the oil into a squeeze bottle, basically like a ketchup bottle so I can squeeze the oil out a few drops at a time in the beginning.  

Well about 1/3rd of the way through I lose my emulsion and I'm left with egg and oil on top.  Should I be using a whisk?  The one I have I feel that the spacings are too far apart but I'm not sure.

How long should it take from start to finish to get this thing made?  I don't know if I'm whisking too long or not...can you even whisk too long?

EDIT 1:  I get an egg and separate the yolk out in a bowl and once i know it's all good I put it into my glass bowl.  After this is done I add the sugar, dry mustard, salt, the vinegar and 1stp of the lemon juice.

I then start to whisk the crap out of this thing until it looks like it's been beat up.  I then start to slowly add the oil.  Just a drop or two at first, then slowly add more.  I'm not sure if I'm adding the oil too fast or put the ingredients in wrong or what the deal is.  At about the 50% mark I want to add the rest of the lemon juice.
It's important to determine whether your emulsion actually broke immediately or was just creaming.

I'm going to trot out this diagram again from yesterday:



(source: Cube Cola)

Creaming occurs when the oil drops, which are less dense than the water, float to the top.  As long as the droplets don't coalesce, you can still fix this with agitation (whisk, blend, or shake vigorously).

Emulsions with coarse particles (of oil) are much more prone to creaming, because their increased buoyancy makes them more able to push up past the water molecules.  You want to have a very fine "mist" of oil suspended in the water; if you were using a squeeze bottle, perhaps the individual drops were simply too large.  A ketchup bottle in particular would not be appropriate for this sort of thing, you'd want to use something closer to a syringe (or just get an actual syringe).

Now if you keep adding oil to a creamed emulsion or let it sit too long then it will also start to coalesce, and coalescence and creaming together are what cause an emulsion to break completely.  This, you really can't recover from, except to let it separate completely, skim off the fat, and start over.

So, to recap:


Your oil drops may have been too large;
You may not have been agitating enough, especially when it started to cream;
You may have added too much oil after creaming had already started.


I also agree with commenter Henrik that the amount of oil sounds a little high; 3/4 cup would be more reasonable for 1 egg yolk.  But since you say you only got 1/3 of the way through, that's clearly not your problem here.