
Pull the hackle down, and make three to four thread wraps around the post to tie off the hackle. Try not to trap too many barbs, so keep your thread wraps below the lowest barbs. Clip the hackle.
You could make a whip finish around the parachute post, but on a small hook like this #17 this is fiddly - to me anyway. That's why I use a reversed whip finish (making turns towards me) behind the eye. This prevents the thread being pulled under the dubbed head.
Clip off the post to desired length. Put a tiny drop of CA glue on the whip finish, on the post where the parachute hackle starts, and on the tie-off point of the hackle, and you're done!