How can I estimate the time required to bring a piece of meat to a certain temperature? I would like to cook a couple steaks using the "reverse sear" technique (e.g. this Youtube video).

The general instructions are:


Preheat the oven to 275F.
Put steaks in oven and bake until they reach an internal temperature of 125F (for rare).
Remove the meat from the oven and let it rest for approximately 15 minutes.
Sear for about one minute per side and serve.


In the video, they use a probe thermometer but without one of these available, how can I estimate the time required for step 2 based on the weight and/or thickness of the meat? Obviously each cut of steak has a different amount of fat, etc but are there any general guidelines? It would be nice to keep the number of thermometer-meat-stabbings to a minimum.
I think this will be impossible to do accurately, in an oven, without a thermometer. I know you want to estimate, but a few degrees will be the difference between rare and medium rare, for example. Variables include: thickness of steak, internal temperature of steak when you begin, accuracy of your oven temperature, and time.  In an oven, even though you set the temp for 275...not only might that be inaccurate (thus the use of oven thermometers), it also fluctuates fairly widely throughout the cook time.  

If you were cooking in a water bath (sous vide) you could solve this problem with excellent accuracy.  See http://www.douglasbaldwin.com/sous-vide.html#Beef

Caution: Do not apply Baldwin's charts to oven cooking.