Better too aggressive than not agressive enough. The contact adhesive has to be completely dry so that it is just the tiniest bit tacky and applied to both pieces, the vinyl and the closed cell foam or it just won't stick. If you wait too long, and the glue is too dry, all you have to do is spray it again to re-activate it. If you want to use the DAP Top and Trim adhesive, it can be applied with a brush, you don't need to spray it.
No one lives forever, the trick is creating something that will.