I wouldn't do it. P&K overuse leads to yellow out.
If you want to "push" P&K wait until week 6 and do it during the bulking phase. And yer still going to get yellowing of your leaves starting bottom up...
Keep in mind that MJ needs N since it's a foliage plant.Too much P or K will lock N out.At the first sign of yellow leaves at the bottom,do NOT feed bloom foods.Go with a high N product.As a matter of fact i am using a 10-3-7 from start to finish.Man she is looking great,smells great,and i've lost a FEW leaves.Green plant=great bud production.
You can mix anything just make sure you dont do it directly the nutrient need to be put into a container of wate seperately or else it will cause the nutes to bog one another out giving you nothing but a funky molasses.