M.M.
What area do you live in? The Arlington Heights park district has a Kindermusic program for infants and babies and offer working-parent friendly hours. If you're not in the area I would suggest checking to see if your park district offers it. My daughter and I have really enjoyed it. I know, there's not much out there for babies that young, esp during evening or weekend hours. Oh-I hear places like My Gym and Gymboree have offerings as well, although they're a little pricier.
Good luck!
MC