Hi Gary,
 
March 5 is in the ballpark, perhaps a bit early but in the ballpark for
these parts (you're mid-Mass, no?).  The trick about early feeding is that
once you start you have to keep it until there's plenty of forage
available when you stop feeding.  The pitfall to avoid is to feed/stimulate
and then leave the bees with brood to feed with no food available.  First
available pollen is skunk cabbage (sorry, no latin name) which starts around
here about the ides of March.  March 5 puts you about right.
 
Good luck!
Aaron Morris