Hi Rweintra,
I booked a couple of PE to UC upgrades over the weekend, for flights next Sept/Oct. I purchased S class PE and used 20,000 miles per flight for the upgrade. I found Flying Club to be really helpful with this, just called them and provided date options and he did the rest. I'm sure this is easier than testing out dates on the web. The thing that really surprised me though is that, even booking 11 months in advance (which is the earliest any airline will allow you to book) our "first choice" dates had no G availability left!! With a bit of flexing though I managed to get the whole thing booked

Cheers, James