How your plants take up the nutes depends on the genetics and your media, water and climate..... Typically people phase in bloom nutes as they phase out Veg nutes or stop veg nutes all together.... I give mine a veg blast right at the start of flower and then just bloom nutes until week 5 of flower, then i give them more veg nutes to hold them off till harvest (indica dominant strains, with sativa dominant strains I give one more veg nute feeding around week 9 and 11)..... but if the leaves show nitrogen defiency too rapidly I will add a small amount of veg (if that happens at all its usually in week 3 of flower, two weeks after the veg nute blast)..... hope that helps......