If it has a layer of beer atop the cake, you should be OK for a couple of days.
Personally, unless I'm going to pitch immediately onto an existing cake (typically not the whole cake - 25-30% for an ale), I like to go ahead and harvest it into sanitized canning jars. If I plan to keep it more than a couple weeks or if it has a bunch of hop gunk, I'll rinse it a couple times.