The thing (one of the things) I like about 505 spray is that you can shift it if you need to. You can take the backing off and reposition it. You can put the sandwiched quilt in the closet for 6 months and then drag it out to quilt and it's still great.
I will generally use about a half dozen pins after I have the sandwich sprayed and together, just to extra secure the edges. And as sparingly as I use it, it's not expensive.