Feminized Aurora, whats better pruning or fim technique?

Hello,

I have 4 young auroras and wanted to top but not sure which is better. or is it topping and fim?
also, how tall b4 i should do this?

Is pruning cutting of the whole top and does fim mean to take like half of it?
sorry for the noob question. i have always just let mine grow.

thank you for your help!!