Hey,
I don't have many comments except to note that April will be COLD! The water will be very cold and even if it's warm on land it will be COLD on the water.
You have 120nm to travel so 3 40 mile days would do it. I would plan on 40nm / day and then if you run into bad weather you can stay in port one day. Personally I would probably go to Newport on day one and get a mooring. Make sure the launch service is running. For day 2 I would get close to the canal, but stay in Buzzards Bay. Then day three would start with the canal transit and then home to Quincy. This assumes the flood tide would start in the morning on day three.
Last August I did a similar trip on reverse when I was coming home from my Portland Maine vacation. After leaving Portland I eventually ended up in Salem. From there I went to Plymouth, then to New Bedford, then Bristol, then Block, then Westbrook. I was on a cruise, not a delivery, so the point was to sail and have fun.
Good luck,
Barry