To the OP: Have you considered booking C awards with Y seats (if available), then waitlisting for C seats? There's a chance they won't clear, but you can grab the segments that *are* available, and you'll be on the waitlist, where you'll be given seats as soon as they become available -- no need to keep checking. If other dates open up, you can change your dates (but not your routing) for free.

Note: In order to waitlist, all of the flights on your itinerary have to be on United.

Good luck! I'm waiting for a Y -> C upgrade to clear, but it looks like they're making C upgrades and awards available about a week before the departure dates.