Might be worth doing this if the SIII is on the horizon by the time your contract is up, however I personally wouldn't hold out on it for more than 1-2 months as there's always going to be the "next phone".
If his contract isn't up until May getting the SII or Nexus would be stupid (the Nexus will be half way through it's life cycle, and the SII will pretty much be dead..)