I'm having trouble with one of the double hits and I was wondering how you all time it.

I'm currently doing

Delphic, auto+slasher, auto+ultislash, auto+slasher, auto+ultislash, auto+slash.

I'm having trouble hitting the 3rd hit, which is the first auto+ultislasher. I'm hitting the ultislash button as soon as the slasher comes off, which works about half of the time. But other time the auto hit doesn't come off, or even worse, the auto hit comes off and the ultislash is done the next round rather than the same turn, meaning I lose 2 double hits. So just wondering how you all time this one. Thanks!