Yo, SammyBoy:
I started with Hi/Lo no side of aces. A friend was using the same except he was counting the 7 not the 2 like me. + he was doing an ace side count. I felt like maybe I was missing something. But it seemed to not make any sense to count the aces twice. So I went looking for another count that would be much more perfect all around. I didn't want to fry my brain either. I got to where I was able to count down a deck with Hi/Lo in 18-21 seconds. I now count a deck in my hands with OII (without side of aces) in about 30 sec. I do the side of aces when in actual play with my fingers. I was able to find the cancellations on the table with Hi/Lo but not yet with AOII. Still doing 1 and 2 cards at a time as they flop. If I get a slow dealer I will look for cancellation sets of cards. Most of my time is spent on the 6 decks.
I don't think in a million years I will get to the speed I was at with Hi/Lo. There is just too much more to have to do. But that's okay, we don't have to be that fast in order to be accurate. Once in a while when I am tired, I find a dealer that is too fast. But that is seldom.
To answer your question as to how long it will take. Heck I don't know. When I decided to switch though, I never flip flopped back a forth. I practiced some then went to single and double deck games. Then as I got faster, found slow dealers on 6 deck. I'll be the first though to say that my mind is not the sharpest in the group. But that's okay I sometimes even amaze myself in other areas. I will say that I'm winning a lot more $ more often now with AOII.
Go get "em tiger.
Stealth