My understanding is that they sea lice are most prevalent in the Spring when the waters start to warm up. We went in March, armed with Safe Sea we purchased through drugstore.com. We didn't see hide nor hair of the sea lice. But the lifeguard said he has often seen jellies at CC.
Didn't there used to be a thread at the top of the page entitled "everything you wanted to know about sea lice..."? I'll check it out.
Edited to add - yep, it's there. Under links to important cruise information.
Denae