Should I give my plant nutrients with Nitroge

I'm using Fox Farm Nutrients. My plants are about 4 weeks old but about 6 days into 12/12. I did not use any nutrients during 18-6 phase. I'm growing in 75% pro-mix and 25% perlite. I added nutrients for the first time last week. I used the Fox Farm feeding schedule and went with Week 5 since I just started 12/12.

BUMP for answer

You can still use Grow Big. Just use it at like 1/4 strength the first time.

I use all three Grow Big, Big Bloom and Tiger Bloom. I'm growing some AK-48 and Master Kush. It seems I have to go very lightly on the FF nutes with these strains.

You should be good. What strains you growing?

I'm kinda wondering the same thing, my first grow is in week 3 of flower using fox farm nutes , and i only fed my plant about 3 times in the month in a half they vegged. Several of them look like they are need a little extra nitrogen (red stems on fan leaves, slight yellowish appearance to the leaves). And I was wondering if it would be ok to use some miracle grow all purpose fertalizer in place of the grow big (Please no mg bullshit, I already know and use it sparingly) But if I did would I replace the tiger bloom with it for one feed or got like 1/4 strength with the mg and 1/4 strength tiger bloom. Right now I'm feeding 1/2 strength tiger bloom full strength big bloom and molasses.