The deliveries will start on Friday and will continue through October.
According to analysts estimations, based on pre-orders so far, the sales for first-weekend could be up to 10 million.
"Assuming preorders are similar to the 40 percent of first weekend sales for the iPhone 5, this would imply iPhone 6/6Plus first weekend sales could be around 10 million," Wells Fargo Securities analysts wrote in a note.
Raymond James analysts said they expect sales of iPhone 6 and iPhone 6 Plus to top 9 million in the first weekend.
"Apple will be selling every iPhone it can make, at least through October. Because of this, the first weekend sales are typically more indicative of supply than demand," they said.