Personally, I'd actually not watch it until you're done with writing.  Why risk influence by it, even accidentally?  

BTW - I've already run across that problem myself with two features, already... Both times, I conceived and wrote the idea first.  Then discovered after the fact that someone had done something simliar.  Fortunately, in neither case were the details the same - because I followed my own vision from the start.  And I'm sure that when/if they're produced, the result would look extremely different.  After all, so much goes into a TV show or film.  The writing, the director, the cinematographer, the actors.  You could have identical ideas, with very different results.  

So - if you have a passion for the concept - follow it!