Switched to 12/12 forgot to do any pruning

At this point I wouldn't stress it. Let it stretch and reevaluate in a few weeks.

I would not do any defoliation on plants this size........in fact I can see no real reason to ever defoliate personally. It is not a required "technique" when growing cannabis.

Hello. I've found that it takes about 3 days for the plant to pick up on the time change. So I think you can go back to 18 hours of light and when your plant has healed in a week or so then turn the light to 12 & 12. Remember if you take more than 1/3 of the leaves off you will be sending the plants into shock and it need time to heal. Good Luck. Chuck.

Do you last big defoliation 2 to 3 weeks after light change to 12/12. So you have not messed anything up.👍🏻

I’m not a big fan of defoliation unless it’s necessary, but if you need to do some, I know a lot of people do the last round of it at about 3 weeks of flower. So, you’re still good if needed then