When did you move to 2 naps?

LO is 5.5 months and is fighting midday nap hard! Usually naps are 9:30,1:30, and 4:30. About an hour long typically. But recently she has not been napping for the 1:30. I just end up giving up and putting her down for next nap around 4. That makes her have almost a 5 hour wake window in between naps??

Does this mean LO is ready to move to a 2 nap schedule. Overnight sleep is good with typically only 1 wake to feed around 4am. She sleeps 8-8. Or 7:30-7:30 sometimes.