Likewise, you can show up around 4:30 - 5:00 pm and get a start on the evening. They usually won't bother you about that either. After 5 it's fair game. Brewster is generous in that they permit us to access it thru the day into early June (vs. Memorial Day in other towns).
There is an option for parking in the area just to the west. There is opportunity to access the same waters but only with additional walking and careful management of tides. This parking is available all the time.
Send me an email if you would like more details.