Honestly most D2's are pretty lenient with timing, just don't do them too early and they'll connect.
Some people just have jumping incorporated into their play style and won't stop even if you anti-air every jump.
Prime example was two nights ago I fought a Sub Zero player (I was Piercing Mileena) who got me first round from doing Sub's ridiculous JIP1 into 50/50/ice clone. I realised this was his strategy and so next round I only focused on anti-airing.
Mileena's B1 in Piercing is a great anti-air, can lead to about 40% if you spend a bar, anyways beat him using only B1 anti-air.
First thing he did in third round was jump 1.....after losing a round from only anti-airs, he just still continued to jump in.
Moral of the story is you need to get your anti-airs down as it can make easy work of people who rely on jumping.