I main Ganon - we make a living out of iDA'ing at the first frame possible after our Flame Choke =pyou are just running too long. You only have 3 frames to dash grab if you don't buffer it, so you should just flick the analog then grab. Our grab has a very good hitbox above the actual whip, while it has a ****ty lower hitbox, so you can grab MK out of the air much higher than it actually looks like.
Or just learn how to buffer it. You can dash grab buffer almost immediately after MK releases and it makes the timing really easy.
So if my Dash Grab Command comes out somewhere between frame 1 to 3 after I'm done with the Grabrelease it'll work properly, right?