Florida Colors Plumeria sells them so you could contact them to see if they say it is a late bloomer (still, I would be concerned as the length of the days is starting to become visibly smaller and that does not bode well for late blooming plants from September and later months). In the meantime, make sure it continues to get more than 6 hours of sun, sufficient but not too much water, and lots of P & secondary minerals in its fertilizer NPK Ratio.
