We do 3 naps and he generally has 9.5-11 hours a night so I think 10.5 is good! X
I'd stick with 3 for a week or so then see if you want to try 2 as 4-2 in such a short time is a big adjustment.
Do whats right for you. My LG has 2 naps and we have a good routine for it now. Wake 0700 Nap 1 - 09:30-11:15 Nap 2 - 15:00-15:30 Bed time - 19:45
My baby has roughly 10 hours a night and 2 naps, so I'm not sure. Might work for you though. Keeping in mind, some babies just need less sleep than others