I like to start with the bloom nutrients once the flowers have formed little budlets and/or tufts, as she will still need a bit extra nitrogen in the first 10-14 days of flowering. I usually stay with the grow nutrients for the first week or so, then go to half strength grow and half strength bloom for the next week or so, before moving to just bloom nutrients. Have been doing so for the last 2 and a half decades and swear by it.
Hope this helps,.......
Organoman.