When is Prime Day? Here's when to shop the Amazon's fall Prime sale.

Amazon loves to keep us on our toes. We've been covering Prime Day for years, and even though the dates vary slightly, we expect Prime Day to fall in July. But this year, the retailer held its flagship sale in June, much to our surprise. This fall, however, things are back on schedule. Amazon's biggest sale of the year may be over, but there's another one upon us. We're here to lay out all the details you need to know…