I was thinking of trying this on my blueberry plants. My HLG 300l rspec is at 200watts (tops out at 250, I think) and seems to be more than enough for them 13-16 inches away. Currently they are in 5 gal pots and finishing up week 5 of flower...when and how would you suggest lowering the light intensity?
A pro here taught me to lower it by 25% and then up to 50% in the last 14 to 17 days before harvest. If they are almost done, you will see how even though you think more light helps, they will do even better this way.
This assumes you hit them hard through most of flower.
Last run I kept temps at 80f or lower and decreased to about 76/77f to finish and had the lights down about 35% at the end from max. The stink level was off the chart, and no foxtailing.
If you plan to run the blueberry say 12 weeks I would start around week 9. If going 14 weeks around week 10. If only going 10 weeks prob around week 8. Have fun with it and if you are like me and push them hard you will like what this does too.
If you have the vertical height available I would suggest raising that light up now and recalibrating at 18 or 20", it will only help ime. I.e. maybe 200w at 12" is same as 250w at 18" and you will get better coverage without risk of burning the tops.
Please note all this is said knowing you already KNOW your sxxx so none of this is "how to", just some thoughts I have.