When do COLA's generally start blooming?

2 and 1/2 weeks into flowering...still waiting on the cola's to fill in...

when does that normally happen? weeks 5-7?

Blooming or filling in? I am at about the same timeline as you with my flowering. I am using 2 90watt T5 (mixed spectrum-heavy on the red) and 4 45watt CFLs (mixed spectrum).

My plants have all shown sex and more and more tiny flowers appear every day. They are blooming now. They will continue to boom for another 5 weeks or so, filling out more and more. About 2 weeks before they are ready to harvest, they really swell up and fill out.

Just keep the soil and flower area dry. Feed them plenty of N still with a lot of P. It will happen, just allow the time to pass.

sorry, I misspoke. Meant, filling in....

here's some more info..

https://www.rollitup.org/indoor-growing/302774-nypd-bubblelicious-hindu-kush-hps.html

You should start to see the main colas forming at around the end of week 4, not counting the 1st week you switched to 12/12. Should be around 4-6in in length by that time as well, depending on how much your plant stretched.

lol at your location.