We had our first NND at about 22 months if I remember rightly and just seem to be gradually increasing the number per week. I think at this age you have to give anything a few days to see if it will work, there's so much that can vary day to day (levels of stimulation, activity etc) so a one-off often doesn't tell you much.
In case it helps, I'll post what we do now. We've done pretty similar for the past few months. DD is at nursery 2 days a week and will either not nap (common) or else take an early 1h-1h15 nap at about 12pm. The other days we do:
WU whenever - can vary quite a lot at the moment from 6.30-7.45 (usually later WU after NND)
Nap - up to room 1pm, in bed for 1.30pm. If she sleeps (getting rarer) then wake her at 3pm. If not try for minimum 45 mins quiet time in room
If it's been 2-3 days with no nap, tactical drive at about 3pm and allow a 15 min catnap if she nods off
BT 6.30/7pm depending on WU and nap
From 22-24 months the NNDs were pretty rare, maybe 1 every 1-2 weeks. Started having a few more (and first episode of 2 NNDs back to back) at 25 months. Now at 28 months getting maybe 1-2 proper naps per week, plus 1-2 very short catnaps. I think sleep needs have gradually drifted down to more like 12-12.5h now whereas at 24 months it was probably more like 13h.
Hope some of that helps!