I don't know any way of calculating exactly when a Jump will land, but check Aerostar's Battle Mechanics Guide at gamefaqs.com. I have heard that your attacks will land if the target's CT is under 50, and so far that has held true in my experience. I don't have any calculations to back that up, nor have I tested it extensively with Hasted enemies etc, but it is a good rule of thumb.

I don't think that knowing how attacks function is cheating, it's just being well informed. Now go jump like a kangaroo.