If I transplant my ladies from 0.6L pots to 8L fabric pots on Friday, can I top them two days later, or should I wait a bit longer?

Hello. Yes... I use topping all the time. I'll remind you it is high stress training HST, so the plant's will take time to recover from that. Just a bit of sulphur on those cuts will heal them just fine without any infection. Most garden centers will carry it. Yes it's a great technic for making a larger canopy. LST won't do that. I use a tomato cage to widen them out. I don't have room to pull them over and use netting to hold them. Yes... you can repot, and top, at the same time but it will take a bit longer to heal from the 2 high stress technic's. It's better to do the 2 technic's a week apart. You've got to take care not to overwater at this point, but let them heal. Cannabis plants will bounce back from HST if you let them heal. Cannabis is a very versatile plant and will bounce back from most training and trimming technic's if you give it time to heal. Good Luck. Chuck.