Yep, it is rather early but not unheard of at all.
I would still expect that first A will be too short hun, if he is nearing the 2-1. Many need to be pushing over 4hrs A to be considered in 2-1 territory. So very close. Fwiw we did this around your lO's age..
Wu 6.30 (normally earlier but aimed to get out of bed around then)
A 4hrs
S 10.30-12 (capped but very rarely need to cap it, if ever)
A 3.5hrs
S 3.30-4.15
A 2.75hrs
BT 7
As you can see I went with the slightly shorter day, but DD tended to take a long time to fall asleep at BT (and still does). She's always preferred a shorter A to BT too like yours. Around now it did take 20mims or so. We held this for around 3 weeks I think, then the shorter am nap came back, as with playing around at nap time so pushed straight to 4.5hrs and we held that for a month or two until we started getting pm nap refusals.
Wdyt? Fancy holding your ideal easy for a couple of days and letting me know what happens? What you're working towards looks great, but there might need to be a little movement in that first nap perhaps soon? Xx