I had males show less then a week into 12/12, and some females not show until after 2 weeks. I flowered rather early for their size so they took a little longer. My clones started showing actual bud development a week into 12/12, but they are clones so they keep their mother's maturity so they are fully ready. Some strains just take a little longer too.

If stuff doesnt change, I would definitely look into light leaks. And yeah, 20/20/20 is to much nitrogen.