I think the most you should jump him is once a week and try jumping no higher than 2"3. When your horse is a 5 year old you can start to jump 2 times a week and any were to 2"9
Depends if he's physically and mentally ready. Probably okay to jump small
It's fine as long as you're aware that they keep maturing till about 7 or so (I think but can't quite remember). So just keep it low and don't over-jump and you should be fine 😊
It depends on the horse, but lunge them over medium or high caveletti so that they can gain confidence and then start short sessions of jumping once they are confident going on the ground.
I jumped mine up to 1 meter high, but he is bred for it and VERY BIG so for him that is a small jump.
Depends if they are ready for it. And likes jumping and the horse needs to be in shape
If the horse is in good shape and behaves well during flat work, I don't see why you couldn't jump him. However as you said, it has to be short and easy sessions so the horse is not disgusted and can gain confidence.
Good luck :)
I have a bunch of 4 year old horses, it depends also if they have good breeding and are born for showjumping. My 4 year old jump twice a week. But usually the biggest I jump is up to 1m