When to change NPK from growth to flower?

My experience is w/ indoor grows and when I changed to a flowering light schedule I switched NPK from 6-2-3 to 3-4-8.
Altho we are still a month off from -12hr light, one of my plants is already showing an abundance of hairs. When do outdoor growers switch their nutes?

***I edited this because I had the wrong NPK***

whan you see flower clusters, after stretch, then add flower nutes.
they preflower in veg once plant is mature, thats when you know they are ready to flower.

By the time I see flower clusters, I switch to my next ratio of 1.5-2-4. So I guess my question is, does anyone change the ratio (lessen Nitrogen and increasing P & K) during this outdoor preflower.

PS...I edited out the wrong ratios in the opening post...

no dont cut down on N til after stretch, feed veg nutes until they are flowering they still need it for stretch period.

Even in flower we reduce it a bit but still feed N.

So, these preflower hairs are too early for any change to flower ratios.
thanks
Yeah, about that stretch.......I'm used to 8-10 inch stretches.
These ladies are already 7 feet