At this point and time you are not going to be able to tell (probably). From seed, depending upon strain (and thus genetics,) it can take anywhere from two weeks to two months before a seedling will be mature enough to start pre-flowering or auto-flowering.

It's easier to tell from clones, as most clones you get will be female (unless you specify a male clone for breeding purposes, which very few places will ever have,) and they will already be mature enough from the mother plant to be expressing their gender, partially caused by the stress of cutting and rooting mature stock forcing it to start the flowering process regardless of light cycle.