Four days round trip? You'd better have JATO bottles and hydrofoils on that boat, or be prepared to keep moving both day and night. Get a copy of "Eldridge", check out the tides you will have to work with, and remember that the sound can be, and often is, WINDLESS in July and August. By the end of July you can have a windless day with 95F heat and steamy humidity, and after 10am you'll be very happy if you've got the engine
to do something about it.
I'd revamp the plans, if you're uncertain and just want to do some fun cruising, sail for a day or day and a half, hang out for a day wherever that takes you, then do the return trip. Don't go for Montauk, it will still be there next year.(G)
Some folks would also go for Oyster
Bay (a full day trip from NYC) or Port Jeff, take a mooring
for a week, take the LIRR home, and come back to do another hop the next weekend.
But between the currents in the Sound, and the light air that can hit in summer...you've got to plan alternatives.