Pre-Registering for the WSOP $1500 events?

[cjk73]

Will be going to the WSOP for the first time this year with the intention of playing a few of the lower buy in events.

My question is would it be a good idea to Pre Register through Harrah's web site or is it safe to just walk up and pay the day before?

I'd hate to get to Vegas only find out one of my desired events was "full" (are the early events ever "full"?). On the other hand my preference is to see where my BR stands as I may want to play a higher buy in.

Anyone have any insight on best practice on this?