Transition to one nap

Crysta • #1 graced us with her presence on June 23 😍 Our sweet Hallie Grace ❤️
Hey!  My girl just turned 1 last Friday and for about a week now she has been terrible with her first nap.  She takes sometimes 30 mins to fall asleep.  Just plays in her crib.  When she does fall asleep she wakes up probably 20 min later and yells and cries until I go get her.  She takes another nap in the afternoon and does fine with that one, but it's still only about an hour long no matter how short her first one is.  Is it time to transition her to one nap per day?  I always heard most babies need two naps until they're about 1.5-2 years old so I thought we had longer!  How long should that one nap be?  Any tips for helping the process be smooth? She sleeps great at night as we sleep trained st 6 months and she always goes to bed (nap or at night) awake.  Thanks!