Most people glass the deck first. Cut out the final cockpit opening and work on the coaming with the deck glassed. (I'm assuming a Nick style vertical strips coaming) Then you can glass the coaming with a strip of glass wrapping it around the coaming. I added my filet after that so it covers the glass joint where it meets the deck. If you filet first, you have the chance of contaminating the bare wood and causing a blotchy look.

The glass strip will hang on the vertical surface fine.