The shortest distance from Hookset NH to Longwood Medical area in Boston, MA is 61.8 miles.

Roughly that should take at a minimum 90 minutes to drive - with no traffic.

Add another 30 minutes to park and walk to your appointment location.

Add in extra time because you are coming inbound to Boston during normal rushhour traffic on a weekeday, so I would estimate 3 hours, plus an hour in case of other problems (difficulty finding the parking garage or the dr.'s office) - ok so four hours, inbound.

Your medical office probably wants you there an hour or two before the procedure. That means leaving Hookset NH around 6am - at the latest - to arrive by 10 am.

I'd leave around 4:30 am because I like to be early for important events.

If it was me, I'd also consider leaving the night before and book a hotel room closer to the city, but that can get expensive. Make sure you gas up the car the day before. Ask the doctor's office where the closest garage parking is to your dr's office. They might have additional advice, since they are used to patients traveling.

Take care, and good luck.