Day 29 she seems small but it’s probably due to the solo cup, I plant mine directly into the posts they will stay in. it can’t hurt to LST her still be careful and go slow, even if you slowly bend it over a few days, mine kept growing a ton after the first flowers showing
She’s probably small because you kept in the solo cup for so long, my general self rule I use which I learned from here, is when the first leaves reach the sides of the pot/cup then it’s time to transplant
But, don’t be put off she will still grow some more, I believe they can still double in size during flower almost, sometimes. But they do definitely still grow in flower, you can still LST I believe, some people LST all the way through yo near harvest, sometimes don’t have a choice if the buds are super heavy you’re in the best place you can be for plant advice here buddy!
If you do autos, you can also just plant them straight into their final container once germinated, so you don’t have to transplanted, the one I showed in the picture is a photoperiod, but same rules can still apply if you wanted to start in solo cups with autos