Group makeup will really determine the amount of time to get comfortable with your setup.
Also having a key layout that is comfortable and easy to use helps with this. The less you have to move your hands around the better.

In my experience with 5 boxing, 1Pally/4Shammy, it took me a good 8 hours playing time to get really comfortable with my N52 Layout and that was after numerous refinements of my keybinds and macros.

It doesn't get any easier as you level though. Each 10 levels you usually get a new ability that you'll want on your spell bars. So you'll have to spend another few hours getting used to that button or messing with alt/ctrl modifiers and getting a feel for what is what on the fly.

Give it time, you'll eventually get used to it just in time to have to redo it all with new spells/abilities.

Oh yea and welcome to Hell!!! Enjoy your stay.