I prefer to have a tab on the ends of the zipper. I will sew a tab at least 1 inch long, on to one end (usually the one where the pull will be when the zip is closed because that is the hardest one to get nice and tight) Then I lay the zip on the fabric for the pouch and determine where the other end of the zip should end. I sew a similar length tab on that end before cutting the zip. ( the longer the tab, the more wiggle room you have. A 1 inch tab will yield about 1/3 to 1/2 inch visible tab after being sewn to the zipper and into a seam. )