last minute upgrades - call Carnival or try at check-in?

[Michelle1959]

I have booked a 1a inner/inner cabin on Imagination. It occurred to me that there might be a few available OV cabins due to last minute cancellations. Would I be better off:

1. Calling Carnival a day or two before sail date to see about any available OV cabins I can upgrade to? If there is one, would it be at such a great rate that I may not have to pay extra for the upgrade or would it be minimal? I won't mind paying $100-200 extra for a 4A or something like that, and I'm travelling solo, also.

2. Waiting till I'm checking in on sail date to ask about any available cabins I can upgrade to.

I don't mind the E189 cabin, but I thought that if there were any last minute cancellations or the ship wasn't full that I might get lucky.

Also, this will be a March 22nd (spring break) cruise, which probably means the ship is likely to be booked full, right?

What would you do?

Thanks!