Yeah, I did the Japanese to curly transition as well a few years ago. My hair needed a lot of protein (treatments or conditioners with protein in it) to recover as I was straightening the curly bits for a while.
While your hair is being tied in a bun, it's a good time to experiment with products and techniques. You have nothing to lose as it's going to be tied up anyway.
Hopefully, by the time you get to do the chop you'll have a pretty good routine/products.
Hair Type: Fine, 3a
Cond/LI: MOP Mixed Greens
Styler: IGA Gel
Overall: Just likes a bit of TLC