follie growth ?

Went for a follie check today at CD11. The plan this cycle was Met +Tamoxifen+Trigger+IUI.  Today I had one follie at 10mm. What is the rate of growth for a follie?  I forgot to ask today and it sounded like this follie most likely will not mature.  I go back on CD 16 and it sounds like they want to see if I can produce something on my own.