Hi mate, good job with this lesson!
I think that you are getting a very good sound of this technique and that the only thing that need some more adjustment is your timing. This element is on of the most difficult things when playing this technique so it's natural that this happens at this point. I recommend you to put more focus on it, and using your foot or your head to feel the groove inside while playing.
This can be also related to a technical limitation that will disappear with more practice so please keep on playing this one and pay attention to timing.
Keep on the hard work!
PS: I think that this lesson (
LINK) can be a good follow up to this one.