I had mine in QT for 2+ weeks and now they are laying eggs!!!
I do not mind snails but I mind the bioload, clean up, etc. If I have to do so much work, I'd rather devote that energy/resource to adding another girl instead.
I did two baths. The first, 30 minutes at double dose. I still saw snails moving around so the second time I did a quadruple dose and removed the adult snails by hand.
I tried removing them beforehand, and I recommend you also do so because the snails will literally look like they are in extreme pain, and any that are hiding will immediately try to get to the surface to get out of the water. They probably won't make it to the surface if they are already at the bottom. Mine made it halfway up the side of the 1/2 gallon QT tank.