Originally Posted by
fumje
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From the inventory, ORD-FRA looks like at best it would clear a week before, while FRA-IAH may clear as much as several weeks before. No guarantee for either.
You can check the actual loads with cablepick.net/united (enter your flight information and look at the flight status page it pulls). Seats aren't a reliable measure, although you can get some idea.
I would also (1) Check every day or two to see if PZ opens up. It can do so, but not automatically upgrade you because of the way the UA system works. But if you call in you might be able to get them to force it. (Sometimes you have to call several times.) (2) Keep an eye on any cash upgrade offers or even just the overall business class price going down, in which case you can buy up without a change fee (called a GG-BUYUP) and get your miles and cash back. (3) Keep an eye on other connecting flights that might have PZ open on them. The change fee might be worth it to get confirmed in business class. I've done all of the foregoing, though now I try not to waitlist, and will wait till the price is cheap or PZ is available, and am willing to look at lots of different connections to avoid economy.