Using super bloom 0-10-10

How much should I use went straight water for 1 week of flower , then started add cal mag supplement. Now I wanted to start fattening them up 4 weeks into flower Strain is jack frost

They will still want a bit N in flower.

it is a booster
add it on top of your base bloom nutrient.
you are week 4, start half recommanded dose, they the week after go full dose if they answer well
keep it until the end