Thanks for all the help guys, and I thought it took 10 frames?? It is really slow (comparitivly) to cancel if you hit someone with it, and I was exaggerating a little...lot.. w/e
Taking hit lag into account, the earliest you can start the jump is the seventh frame. The shine goes like this:
1st frame: Hits, Fox is invulnerable
2-3: Shine is neither hitting nor reflecting
4: Shine starts reflecting, jump can be started on this frame.
If you hit someone, you get 3 frames of hit lag, he/she gets 5 (normally both players get the same amount, but attacks that electrify the opponent give them about 1.5 times more lag.) Once again, assuming perfection, the shine would go:
1: Shine hits, Fox is invulnerable
2-4: Fox's hit lag. The shine is "stuck" in the first frame during these three frames.
5-6: 2nd and 3rd frames of the shine's animation. It's not hitting nor reflecting.
7: 4th frame of the shine's animation. Starts reflecting, jump can be started on this frame.
You'd be in the initial jump animation from frames 7 to 9 (Fox's jump animation is 3 frames) and you'd be able to air dodge on the 10th, which would put you back on the ground immediately. You have 10 frames of lag when landing from an air dodge, so you'd be unable to act from frames 10 to 19. You'd be able to input your first action after the waveshine on the 20th frame.
On the other hand, after the first frame that the shine hits, most characters that stay standing have 33 frames in total of stun (5 frames of hit lag, 28 more frames of stun). They'd be able to put up their shield on frame 34. Overall, you have 14 frames of room for error and/or walking/running a bit closer to the opponent.
Anyways, back to the topic at hand, do what you need to do. If you feel it's better for you to switch hand positions, then do so. In that case, learn to switch positions as quickly as possible.