I am also learning this combo and I thought I'd share my experiences with you in case you find them helpful.
I think the delay between j.B and j.A is the most important delay. Not giving it enough time is what was preventing me from executing the combo consistently for a long time. If I land the j.B while high in the air and delay the j.A a lot, I have an easier time landing the 2C than if I land j.B really low and then do a smaller delay into j.A. Maybe there's more downward momentum if you have a larger pause between j.B and j.A. I'm not sure. In any case, I was executing the combo like this at first:
[stuff] > Hop (or delay) > 2C > jc > large delay j.B > large delay j.2A > AD > large delay j.B > small delay j.A > 2C > [stuff]
Then I transitioned into performing the combo more like this:
[stuff] > Hop/Delay > 2C > jc > small delay j.B > small delay j.2A > AD > large delay j.B > large delay j.A > 2C > [stuff]
I find the new method much easier, and I'm landing the 2C much more consistently now! Also on the second j.B, the main thing you want to make sure of is that your opponent is below you. Since when you do the j.B, your opponent will travel upwards and you'll start traveling downwards, if you aren't above your opponent, he'll float too high for you to land a delayed j.A. Because of this, the delay (or hop!) before doing your first 2C is pretty important, as leaving it out will cause your opponent to travel higher. It's still possible to perform the combo without the delay, but it is harder.