I generally hold off on bloom nutes until they are fully in flower unless you want them to stay short ... no need for that ... hold off for a week to 10 days ...
I usually do bloom booster once blooming starts, but stay with grow nutrients for another week or more. Then I do half grow and half bloom nutrients until they are in full bloom. That saying about every day counts in the life an auto is so true. Makes me think of a drag race.
Right on I'll up the grow nutrients next batch of nutes(mixing tonight) and wait for these babies to go in full on flowering. How you tell when they in full on flowering?
Your photos are in full flower ... so a few days before the buds look like your photo buds look like currently ...
The formation of hairs will tell you it is blooming. I consider full bloom when it has stopped stretching. That takes 2-4 weeks for most autos. If you are using the flora three part series, do the transition formula when it is blooming and stretching. Then you switch to the final formulation. The longer they stay in vegetative growth the bigger they finish. The extra week or two will make your plant up to four times bigger.
Damn I was hoping you wouldn't say that because I never checked on them for 4 days due to heavy rain and then next thing I knew they had that bud on them. Kinda just called it on the photoperiods and just decided if they make it they make it so I neglected them a bit.
At some point the autos' buds will look similar to the photos' buds ... at that point they are in full flower ... many new growers switch to bloom nutes at the first sign of sex ... that's generally about 7-10 days early for max yield ...