When should I start using bloom nutes, going to use fox farm big bloom bembe tiger bloom cha ching and maybe big bud?

If you're seeing pistils, your autos have entered flower and are ready for tiger bloom. I would start slowly introducing it at a half or quarter dose and ramp up to full dose over the course of the next 1-2 weeks.u don't know much about Bush Doctor but I'd suggest doing the same of starting low and increasing over a week or two to the full dose (or where your plants start showing signs of nute burn).