Hi Carol - if you go down into the Hobbies forums, there is a forum specific to birding - your question would better be asked there. There are quite a few threads about hummingbirds there, including a link to the migration map of hummingbirds.
That said... I usually see my first one sometime between May 1st and 4th here, but haven't seen one yet. But that could also be because I just put my feeders out 2 days ago.