Your plant will still need nitrogen at the beginning of flowering, and in general, as indicated by its yellowish leaves.
Now that you have gone to 12/12, she will need a bit extra nitrogen to help with the "stretch" and basic flower formation. Changing to bloom nutrients should only begin once small "tufts" of pistils have formed at the end of the branches and the top of the main stem.
Hope this helps,...........
Organoman.