Downtown Wine & Spirits in Somerville's Davis Square marked its first sale of a new era about 10:05 Sunday morning with a single Pabst Blue Ribbon tallboy.
"I don't work today, so why not have a beer?" said Peter Mundowa, its purchaser.
Mundowa, 26, an unwitting pioneer, was one of dozens of Patriots fans, birthday party attendees, and brunch preparers to become the first Sunday-morning alcohol buyers under a new Massachusetts law that allows package stores to open as early as 10 a.m. rather than noon.
Approved by the Massachusetts House in March and by the Senate in July, the law was cosponsored by Representative Elizabeth A. Poirier, a North Attleborough Republican, who said it would benefit stores along the Bay State's borders with New Hampshire and Rhode Island, where Sunday morning sales are allowed.
Frank Anzalotti, executive director of the Massachusetts Package Stores Association, said store owners have mixed feelings about the change. "This will take a while for all this to settle, so I have no idea how many of the 2,000 stores will be opening earlier," Anzalotti said.
The Boston Licensing Board received only a few inquiries regarding earlier opening hours but expects more, said Kate Norton, a spokeswoman for Mayor Martin J. Walsh.
An official at the Alcoholic Beverages Control Commission did not respond to requests for information over the weekend.
At Gary's Liquors in Brookline, Sunday's first sale was to Aimee Ganter, 28, of Manchester, N.H., on her way to a family birthday brunch.
"Everybody there is going to be having bloody Marys, but I don't really like tomato juice, so I'm going to be having Bailey's and coffee," she said.
Jamaica Plain resident Linda Cohen, who turned 68 Sunday, stopped in during her morning errands to find after-dinner liqueurs for her birthday party. She had not heard about the change in the law and was pleasantly surprised to see customers through the windows.
"I came by to see if Gary's was open, and I doubted it, but people were moving," she said.
Owner Gary Park said in an interview on Saturday that opening at 10 a.m. meant adding two hours to the workday for him and his employees, who must be paid time-and-a-half Sundays. But it allows them to sell to tailgaters driving to Foxborough in football season and to beachgoers in the summer.
"As my wife said, I'm probably going to be the richest man in the cemetery," joked Park, 47.
At Blanchards Wine & Spirits in Jamaica Plain, the management moved both opening and closing forward an hour, to 11 a.m. and 7 p.m., to maintain a single eight-hour shift for employees, general manager Mike Denson said Saturday.
He said the store previously had up to 15 people waiting at noon Sunday, and that the noon-to-1 p.m. hour was busy.
Only one customer waited out front at 11 a.m. Sunday, but the next half hour saw a steady trickle of shoppers.
"I didn't know what to expect . . . I was surprised that we have this many people," said Doug Michaud, 24, a manager.
Ernest Paulin, shift supervisor at Downtown Wine & Spirits in Somerville, said not having a crowd waiting upon opening "alleviates a bit of pressure."
"We have the luxury of opening the store and then serving people," said Paulin, 28. "It's a little more relaxed, which I consider a boon."
He said he was surprised to see that one of Massachusetts' notorious "blue laws" restricting Sunday retail was changed in a low-key manner.
"It's funny that one would just roll over and die with such little resistance."
Material from the State House News Service was used in this report. Jeremy C. Fox can be reached at jeremy.fox@
globe.com. Follow him on Twitter @jeremycfox.
Anne Steele can be reached at email@example.com. Follow her on Twitter @AnneMarie