Cancel the order! I'm serious. Flea collars are junk and don't work. Also they cause more problems as the poison is on the collar and if another pet chews on it or it gets caught in your cat's mouth, you'll have a dead cat.
The only good thing to do with them is cut them up and put them in the vacuum if you have a flea problem.
There are better ways to treat for fleas - Advantage or Frontline is a much safer and more effective way to prevent fleas.