J.S.
Tons of stuff to do! My nanny takes my little one on what I call the "pro-library tour" all week. You can find out when the storytimes are and make a chart so you know where to go each day. For example Monday they might go to Braintree then Tuesday it's QUincy then Wednesday it's Weymouth then Thursday it's Dorchester.
Also the South Shore YMCA (branches in Hanover & QUincy) has a bunch of children's programming
I have no idea what the music together thing is.
There is a gym in Norwell/Hanover called Fit Mamas Move and it's supposed to be great but I've never been there. The woman who started it used to be a trainer at FItness Unlimited in Milton where I go. ANyway, I think they have classes for moms/kids together.
Good luck!! Enjoy that little one!