Hello Emulated, to answer your question.
You can grow the seed starting under 12/12 lighting, but sex will not show until it is sexually mature.
This might take anywhere from 3 to 6 weeks depending on strain and genetics. This can all depend on
your grow room setup; lights, ventilation, nutrients, pH, medium, etc.
IMO, I think its a waste of time to do this as it will severely affect your yield for the worst.
Instead you should veg them until theyre sexual mature then destroy the males and flower the females.
Your yield will go up significantly if you veg them out at least 4 weeks before flowering, provided you
have the room or invest some reading into Low Stress Train or Screen Of Green. It can take about
4 to 7 weeks veg to reach maturity. Also since your using bag seed you will never know what strain it is
and if its genetically superior or inferior. Because of this it may just hermi on you because of genetics.
GL to ya