Hi Micah's mom,
Thinking back, I think that Nathan's wake time at 4 or 5 mos was about two hours, with morning nap, afternoon nap, and evening catnap. But like John and Zoe's mom said, I would just go with his cues. We went for a long while where we were giving the evening catnap only if he needed it - so for a month or two, we were really in between 2 and 3 naps. Good luck!