A patchwork of regulations has spread in Canada as each province takes its own approach within the framework set out by the federal government. Some are operating government-run stores, some are allowing private retailers, some both.

Alberta and Quebec have set the minimum age for purchase at 18, while others have made it 19.

The provinces also have been able to decide for themselves how much to mark up the marijuana beyond the 10 percent or $1 per gram imposed by the federal government, and whether to allow residents to grow up to four plants at home.

Steve Hawkins, executive director of the Marijuana Policy Project, a Washington-based lobbying organization that has been pressing for legalization since 1995, said it is time for the U.S. to follow Canada’s lead.

“Canada is setting a strong example for how to end marijuana prohibition at the national level and replace it with a system of regulated production and sales that is largely governed at the local level,” he said. “The U.S. and other countries grappling with the complexities of such a significant policy shift will have an excellent opportunity to learn from the Canadian experience.”

As Canada welcomes legalization, supply shortages could develop, as happened in some U.S. states when legalization arrived.

Trevor Fencott, chief executive of Fire and Flower, said his company has 15 Alberta stores staffed and ready to sell marijuana, but the province has supplied only enough product to open three of them Wednesday.

“We’re aware of some of the kinks or growing pains that come with creating an industry out of whole cloth in 24 months,” Fencott said.

Clarke and Brenda Tobin, who is opening a store in Labrador City in Newfoundland and Labrador, expect to sell out quickly after not getting as much from licensed producers as they ordered.

“We expect to run out. I don’t know the first day, but I don’t expect we’ll have it too many days,” Tobin said.

Tobin and her son Trevor plan to open their pot shop at 4:20 p.m., a reference to 420, slang for the consumption of cannabis. Tobin, a longtime convenience store owner, said they will be cutting a ribbon and cake.

“We are just ecstatic,” she said.

She doesn’t expect to make much money off the pot itself, noting Newfoundland’s 8 percent cap on retail pot profits. She hopes to make money from pipes, bongs and marijuana paraphernalia.

“There’s no money in the product itself,” she said. “You got to sell $250,000 worth of product in order to make $20,000. That’s not even paying someone’s salary.”

Ontario won’t have any stores open until April, after the new conservative government scrapped a plan for state-owned stores in favor of privately run shops. British Columbia on the Pacific Coast will have just one store open on Wednesday, but many more are expected to open in coming months.

Brittany Guerra, 30, shut down her illegal dispensary in Hamilton, Ontario, last month so she could open a legal store next year. She has been a pot activist for more than a decade and never thought this day would come.

“Everybody would say, ‘It’s never going to be legal, you are dreaming,'” but obviously it worked,” she said. “We do feel vindicated.”

The Canadian government is also expected to announce that those with a criminal record for marijuana possession of 30 grams or less will be able to apply for a pardon when the drug becomes legal, according to a senior government official.

The official was not authorized to speak publicly ahead of Wednesday’s announcement and spoke on condition of anonymity.