People tend to check in during these times:
National park service does great job. Friendly, knowledgeable, fun.
Do NOT miss the final stop on the guided tour: John Adams' personal library. This impressive collection is housed in a building to the left of the main entrance.
In 1735 John Adams was born in the colonial saltbox house on this site, and lived here until his marriage to Abigail (Smith) Adams in 1764.
Take a walk around the gardens for free anytime and picnic in the field.