Two weeks is about the length of time that you should DEFINITELY see pistils within.
Just FYI, regenerating a plant is pretty stressful. If you go that route, allow LOTS of time before flowering again- like, at least 2-3 months- to reduce stress and risk of herms. It will take at least a month to re-veg, and then the plant has to have a chance to return to normal vegetative growth, etc.
Plus the soil that the plant has been sitting in is probably what, at least 4 months old?
MAke sure your conditions are correct and if you ARE seeing SOME pistils, you should be okay, but keep an eye out for herm flowers.