Here's how it has worked in the past --
In a few days, Spragg will start a list of high bids for each lot -- posted via a link on the front page of ccgtcc.com. So you can see if your bid has been beaten or not.

There is a cutoff date, at least a few days (maybe a week?) prior to the convention. So you may still be outbid before the night of the auction. And of course, there's live bidding on the floor too, so you could be outbid there too.

Hope that helps.