It can depend on your source water.
what is the EC of your source water?
What amount of Ca and Mg is in your nutrients?
Most of us use a basic A/B formula
seedling early veg 0.4-0.6
Mid veg 0.6-0.8
Late veg 1.0
Early flower 1.0-1.2
Mid flower 1.0-1.4
Late flower 0.6-1.0 reducing slightly towards the end.
Harvest.
I have to use Calmag in my mix almost every time due to my Source water 0.2EC and my nutrients containing 4% Ca and 2% Mg.
Personally I don’t buffer my coco ( canna coco pro) I don’t even rinse.
I just mix 0.4EC and start using it.