Seems to be a common thoughts that the Dr Earth dry amendments last around 3-4 weeks in the growing medium and takes a couple days to get broken down and usable for the plant to start taking it in
a lot of auto flowers start to flower around week 3ish
Zkittles autos depending on the breeder you got it from seem to be ranging in flower times from 9-12 weeks (mine seem to go longer to finish by a week or so from the breeder info)
Thinking on a 10 week finishing time I would shoot for your top dressing around week 3 for “early flower” with a more balanced blend of all purpose and flower girl and your last top dressing around week 6-7 to finish flowering heavier on the ratio of flower girl to to all purpose.
I have had luck following these ratios
2-3 tablespoons per gallon of growing medium
Amended planting medium at start 70% all purpose 30% flower girl
Early flowering - first top dressing 50% all purpose and 50% flower girl
Mid flowering 30% all purpose and 70% flower girl
All plants are different and take different nutrient requirements...and yes wise to learn the stages of how cannabis grows as well.
But this should help you through that learning curve until you are able to understand and learn how the plant will let you know when to feed
here is my current grow journal with dr earth although I use coco coir and also use the 3 part Dr Earth all purpose, veg and flower girl
This should help you too.
Namaste
Red