I've been practicing for about a month and I'm pretty confident with it now. There's not really that much fear of doing it incorrectly since you'll know definitively if you're doing it right or not within 10 seconds. Might just be me, but really the only scary part is the final few seconds before passing out, and even then it's not that bad. And at that point you'll have very little control over your arms, so there's not much chance of you being able to undo it in that short time span in the unlikely chance that you're unable to push through those few seconds. And as long as you do it in a secure position, there's not much chance of you undoing it after passing out. They used a different method, but
this should be similar enough to what will happen after passing out.
If you don't have a lot of time to practice, then sure this method might not be for you, but otherwise I don't see any problem with it as long as you practice it enough.
Tonight is the night for me by the way, if everything goes well.