Hi and welcome to BW!
Here is a great article for overall info and options on the 2-1 nap transition.
https://babywhispererforums.com/index.php?topic=163278.0I was in the exact situation and at first, I gave DS (dear son) a 15 min catnap at 9:00 to get him to a decent nap time wo losing it since he woke so early. I drove him to do this bc I knew he would wake when I stopped the car. You could apop (accidental prop on purpose) this nap in a sling, stroller, etc... or see if he'll sleep for 15 min in his crib. Then I gave his pm nap at 11:30pm and BT (bedtime) at 6:30. Every few days or even a week later, I would move the pm time later by 15 mins. And moved the cn later too. When his wake up time finally moved toward 6am, I dropped the cn and put him down at 11 or so for one nap. Some babies extend to 2-3 hrs, others stay around 1-1.5 hrs. DS had shorter naps so once we got to 1 nap, we switched the cn to the evening around 4:30/5:00, then BT AT 7:00/7:30. Once his wake ups were consistent, I moved the one nap later by 15 mins. Every few days. So 11:15, 11:30, until we got to about 12:30.
This is messy transition for kiddos like ours so expect some back amd forth from 2 and 1 nap. Some days when he wakes early, do the former 2 naps.
Hang in there! You all will get through it.
Love that your first loves sleep. They are ao preciously different aren't they?