How many days are you planning on doing this in, and how many crew will you have aboard. Assuming you and your crew are experienced enough, and the boat is in good enough shape, this is doable. A good weather window is a requirement... and trying to do this on a fixed schedule is foolish at best.
If you wanted to do it in the minimum number of legs, stopping between each, you might be able to make it in three legs.
The first leg would be from Fall River to Nantucket.
This would be about 80 nautical miles and if the wind is out of the southwest, you could sail most of it. Intermediate harbors you could bail at are:
Sakonnet Harbor, RI
, but this can be a bit tough without an engine.
Martha's Vineyard if the wind is out of the South, SouthEast, East or Northeast or
on the SE side of Nashuon Island if the wind is out of the North, NorthWest or West.
Having the intermediate harbors to fall back on would allow you to shake down the boat a bit and get any small problems solved before continuing on.
The second leg could be from Nantucket to Provincetown.
I would go North from Nantucket harbor and then east, around Great point and then go along Great Round Shoal, off the southern tip of Cape Cod, using the Great Round Shoal channel. Then north and around the tip of Cape Cod to Provincetown.
This is a longer leg and it is about 90 NM... again, if the wind is out of the southwest, it can probably be sailed most of the way. However, the stretch around Cape Cod can be a tough one, if you don't have enough crew, as the southern and eastern sides of Cape Cod can be unfriendly—especially since there aren't really any real harbors to bail out at. The only one that might be a possibility is Nauset Harbor and it's not a good choice most of the time.
The last leg would be the shortest, and is a relatively easy hop from Provincetown to Boston.
It is about 55 NM. Again, there are no real places to bail out, since you're just crossing Cape Cod Bay and Massachusetts Bay.
You could also cut directly across Cape Cod Bay and stop in Duxbury or Plymouth, and then go north along the western side of Cape Cod Bay and Massachusetts Bay into Boston Harbor. However, if the wind is out of the South-Southwest, the sail from Provincetown to Boston is a nice reach...
I'd highly recommend you rent an EPIRB for this trip. BoatUS has an EPIRB rental program
I hope this helps.