would just continue feeding you higher nitrogen fertilizer till you plant shows signs of starting to flower and then switch, its probably going to be very soon.
have never really seen nitrogen levels so high that it would stall flowering and suspect most fertilizers would not slow flowering at all, but the biggest reason to cut back on nitrogen would be so you dont affect the taste of the buds but you should have plenty of time to reduce the nitrogen levels once the plant shows signs of flowering by switching fertilizers to one with very little nitrogen and possible just use nothing but water the last couple of weeks.