Went to Pets at Home today. Followed instructions on bag. Float for 15 mins, then add aquarium water to bag, then leave floating for another 15 mins, then introduced snails to tank. Aquarium lights off for an hour more.
One of the snails seems active and with a healthy shell. The other seems much less active and the shell is somewhat damaged. Hopefully they both make it but my hopes aren't so high regarding the second one. In the store I tried to pick two that were hanging off the sides just to be sure they were alive, as a lot of the ones at the bottom seemed dead or empty shells.