When do I switch foxfarm nutrients?

Hello If you were going indoors you'd go off the light hours and start bloom at 12/12. But with us outdoor grows i would usually bring in the open sesame as soon as there was a good boost of preflowers but in nice low doses once a week or two weeks. My outdoor typically starts to flower here at the beginning/ mid August, so i would go ahead and start the tiger bloom at some low doses now until you see the flowers develop and then start using full doses.