When to start using bloom booster? (pics)

I've got a plant, about a week into flowering, and it's looking female. I've been giving it the high nitrogen fertilizer for now.

I am wondering when I should start giving it the high phosphate fertilizer?

The fertilizer I'm using is 15-30-15 so there's still some nitrogen in there. Should I start doing it next time I feed? That's what I'm probably going to do.

Or should I wait until I see buds forming?

I can post more pics if you'd like. This is my plant that I had a long time ago that got sick but recovered.

here is a link to the thread:
http://boards.cannabis.com/indoor-gr...-transfer.html

i've decided to keep this plant small.

btw the lights i have on it are

2x42w cfl
6x23w cfl
1x13w cfl
2x40w fluoro tube

I'm almost a week through my flowering as well... I have a 10-52-10 solution and I am planning to apply it the next time the plants ready for a watering, maybe tomorrow... so I'd say anytime you're ready
http://boards.cannabis.com/indoor-gr...g-you-kid.html

Bloom ferts I generally start on day 1 of 12/12. You will need N in the first few weeks, to help the plant survivie healthy to a later time when you deprive it and most recipes ramp up the P and K values while dropping the N as the weeks progress, eliminating it altogether by week 5-6