9. Rig It
It is likely you will buy a mast/boom with the sail, if not you will have a mast already for it, so rig it. Do you get the loose leech in the right position if you trim it like it’s written on the sail (+-a few cm)? Do the battens rotate when you mount the boom like recommended (+- a few cm)? How does it look overall? Creases or folds where they shouldn’t be.
Also rigging allows for one final key test, is the mast sleeve completely intact. Meaning can you get the mast all the way to the top of the sail without it getting caught in some ripped stitching inside. Often a common repair on used sails and one that is quite costly. There are one or two sail brands that put their stitching on the outside of the mast sleeve (Sailloft, Ezzy, etc..), you will never have this problem with these sails.