I like adding PK boosters in weeks 4-6 or 4-7 or 4-8 depending on how many weeks the plant should be in the flowering stage.
Not familiar with those, wk 2 of flower larger P smaller K, and in a few weeks the opposite. With your nutrients hopefully they have a schedule and if so id stay with that and adjust if needed.
Are using straight phosphorus and potassium or nutrient line mix?
I'm using H+G nutes.
Can either add Canna pk13/14 or CX nutrients bloom booster
Are you in veg or flower?
Week 2 flower