Pre-Flower(?): What should I consider?

I typically will continue the LST period through the pre-flower stage a little longer. The way I judge is to see how much give (lightly) that it has with the type of LST device you are using (pipe cleaners, stakes, etc.). If it still has a good amount of give, at the stage you are at now, you can keep on with the LST in my opinion, even if it's an auto-flower. Once the plant begins to pop out those little stigma-filled bud sites all over and the side branches begin to become more "woody" with less give (and remember, check the give gently), then I would remove the LST. As far as nutrients, keep to your plan that you have going. Keep an eye on the leaves for yellowing and the such. Sometimes when I have had plants enter the pre-flower stage they may get a bit more thirsty. I hope this helps! 👽