Technically you don’t need light until you see the leaves actually poke through the soil but I always keep my light on throughout this process. Find a light schedule that works for you in this stage. Here are a few examples. 24 hours lights on, 20 hours on 4 hours off (complete darkness), or what I personally use is 18 hours lights on 6 hours off. Keep it on this schedule for 6+ weeks at least before you consider flowering