Stow is West - you can get there from Rt. 2 but B and I have always taken Rt. 20 to 27 (the more backroadsy way).

From Waltham it took us 1/2 hour to 45 minutes. From Framingham it may take about the same amount of time or perhaps a bit less. You could try a mapquest direction search and see what that tells you (because there would probably be a smarter way to go from your area than coming to Waltham or Framingham first) :)