When did your LO move from 3 naps to 2, and did you have a normal time/length for them?

My 6 month old is starting to be pretty difficult to get down for naps, and I'm starting to think about trying to transition him from 3 naps to 2, but am not sure if it's too early for that. It used to be that he'd wake up at 7 and nap from about 9-10, 12-2, and 4-5, then bedtime around 7:30 or 8:00. Lately his first nap has been so incredibly short that he gets crabby again pretty quickly, but isn't ready to go down for another nap, so I'm getting ready to try out some different nap schedules.