Should I defoliate now or hold off longer? (just switched to 12/12 )

i would say leave her be, you have plenty of room for light penetration. so if i was you i would bend down the main cola so the side branches and lower branches get as big as the main branch or cola area. this way there is little to no stress to the plant and you get a nice harvest as well. now you can take just a few of the bigger leaves off this week and just a few off next week, but if you take too much off you may loose out on a harvest. i say no but in the end it is up to you

If you're gonna do it, then do it within the first, and no later than the second week after going 12/12. Personally, looking at your plant, I wouldn't defoliate it. It looks fine with plenty of room for light to reach lower parts. ´ - Maybe take a couple of the biggest leaves if you absolutely have to, but a defoliation might just end up hurting your end result if you aren't careful with how you go about it.