Here's what I do. Run a strip of DST along the edge of your fabric (regardless of whether it has a plastic overlay or not). Remove the top paper and stick your zip to it as shown. No need for tacking (basting) or pins. Really quick!
Then sew 1cm in from the edge using a zipper foot and hey-presto you're done and your zipper is aligned beautifully. PS: sewing in 1cm from edge is to ensure your needle avoids sewing through the DST as it can get a bit sticky. However don't panic if this does happen, you can clean the needle with eucalyptus oil afterwards.
TOP TIP: Recently I discovered you can buy a roll of DST from The Reject Shop for - wait for it - $2.00. Normally a roll half the size costs me well over $10.00 from Lincraft or Spotlight.
I was a bit skeptical that it would work as well and used it on a project on the weekend. It worked perfectly.
That's all for now - I have several exciting projects on the go - pictures are forthcoming.