Thats how male AND female flowers look before they develop, give it some time, if it gets double that size without pistils then get worried
EDIT: And generally speaking, pistils develop first at the top and work their way down...
But as a general rule of thumb, if your flowering before you get definite female preflowers (its like a calyx with two tiny skinny little pistils) on the 8th -12th nodes (not all but one of them will have it) then you're flowering before its mature and you wont ever get that plant to its "peak".
Hope this helps.