Joyce Kelly found this good information in a 1982 Jones & Scully catalog. Pot size in standard size plants can help you guess when the plants may bloom. This is part of that chart:
Pot Size…………Years ‘till Flowering
2”…………………. 3-3 ½
2 ½”……………… 2-2 ½
3”…………………. 1 ½ – 2
4”…………………. 1 – 1 ½
4 ½”……………… 6 months – 1 year
5”…………………. 6 months – 1 year
6”…………………. flowering size