Let me know how those plants like that hot sauce!!
Totally kidding. Well a lot of good advice here already. A few mentioned lollipopping the plant which will help the plant focus on its upper 2\3's of itself and putting its energy into the bulk of the yield versus wasting time on the lower branches that would have made "popcorn" buds. You are 3 weeks in so its just starting to get good!! I would say to watch your waterings and avoid over watering, avoid using too much nitrogen at this point, supplement your waterings with unsulphered molasses, tie down if you can a few of those branches to even out your canopy to allow more light penetration to all of those bud sites aka LST'ing, and if you have the option adding c02 enrichment is very beneficial. You can also look into feeding them some good ol' organic tea made from the organic matter of your choice to really boost them in flower. Lastly i would say to invest in a good 30x-100x magnifying glass/jewelers loupe/etc., so you can really monitor those trichomes come harvest. This way you know exactly when they are ready and you don't miss out on another few weeks of critical flowering or risk having them flower too long and not getting the desired buzz you want. I truly hope any of this helps you. Peace and Love all!!