Just feel the horse and get in position when taking off
It will come naturally! Just be patient and it will come!
Don't try this unless you have a really good horse, but I used to close my eyes a few strides before the jump (small jumps only!). It forced me to go by feel and helped stop me from getting ahead of the horse.
When he takes off to jump
Just go with the horse, eventually it will just come naturally 😊
I count my final 3 strides whilst cantering to a jump. So after I count 1,2,3 I get into position just after 3. You'll eventually get into the groove of things. Good luck !