I can see some pistils in some of the photos, so she could be female, but I can also see signs that sadly she may go hermaphrodite. Not definitely, but from my experience, she/it looks a bit strange and would be making me very nervous if it were my plant. Hopefully not, but..........
The plant flowering earlier outdoors is probably due to the days getting shorter triggering a flowering response in that plant.
Maybe reducing your light to 17/7 from 18/6 could get this one flowering sooner and 17/7 won't affect your yields or plant health at all.
Hope this helps, Organoman.