Too early to tell. You need to look for the 2 white hairs in the "V" shape for females, or small round balls, which are males. So far, I don't see any signs of either. When did you start flowering? You usually get some signs in a week to 10 days after flipping... more or less.
Preflowers are usually pistils (the while hairs) that show up sometimes during growth. They are a sign of a female but the two horn looking things are not preflowers... I can't remember the name for them but they don't have much to do with determining sex, despite some folks thinking they can tell by the shape or number of them.