Instead of checking when your try build is complete, this short python script checks try every 5 mins (you can change the interval if you like) using the treeherder API to see if your try push is complete. Gives you a simple notification in your Notification Center (on Mac OS).
chmod +x try_to_notify- (Optional) Move to your /usr/local/bin and remove .py extension
try_to_notify [sha_of_the_try_push]