Unless it's an auto flower you won't see flowering with lights on veg cycle. Sometimes males will start to show "balls" at about 4-5 weeks and females show tiny preflowers about 5-7 weeks. Although not always. Google how to sex a cannabis plant. Very easy to follow guides there to help you Id the plants sex. Otherwise flip lights to 12/12 and wait. Should see flowers starting to develop 3-7 days later.