Although Prime Day is scheduled for the 12th and 13th of July this year, there are offers available now from Amazon and Prime Video, the later being film rentals at $2.99 and lower.
Details are available at Amazon.ca and Amazon.com. And yes, Canadians with a prime membership in the states can take advantage of the offers at the latter. But you can only use the free shipping offers there for American addresses, which is fine if you have a lot of friends and relatives in that country. Or if you have a second residence or vacation home there.
I believe Americans can also purchase a prime membership here in Canada to ship some of their Amazon.ca orders within Canada.