Truthfully if you want the 55 and are going to wrk your way up to it anyway... start with it. it gets very expensive to keep upgrading (from experience
).
Also like jeta said it give you a failsafe... if something goes wrong it goes wrong FAST in a smaller tank. Are you looking at planted as well? What type of substrate.
One thing to consider is do you want do you want in the tank besides the fish. If you are going to want live plants in a few months, start off with the lighting NOW so you dont have to get to light fixtures. If you do the 10 gallon to start tho... you can try sand or something like that which will give you a chance to see if you like it first.