There are several schools of thought regarding cork treatments. Many folks say that they are fine to use dry (with a floor or bench corker - with a hand corker they are too hard to compress when dry), while others say a long soak in a metabisulfite or no-rinse sanitizer is what they prefer. I tend these days to simply rinse my corks with a metabisulfite solution (about 5 mins total exposure time to the liquid), and go. I used to soak them longer, but I've found that they really don't benefit from absorption of much liquid - my floor corker can handle them with just a quick rinse.
Don't drop them in boiling water, since heat accelerates the breakdown of cork cell walls and will actually prematurely age them.