Apple Inc. (NASDAQ:AAPL) already announced that it took more than 4 million preorders for the iPhone 6 and iPhone 6 Plus. Now investors are looking ahead to Sept. 22—the day when Apple will probably announce its first weekend sales, just as it has in the past on the first Monday after an iPhone launch.

Apple Inc. iPhone 6 First Weekend Shipments May Disappoint

Apple already sold millions of iPhones

In their note dated Sept. 17, 2014, Bernstein Research analysts Toni Sacconaghi, Eric Garfunkel and Jonathan Cofsky said they see the 4 million preordered iPhone 6s as being a positive. They note that iPhone 5 preorders were double those of the iPhone 4S and that units rose 30% year over year in the next quarter.

A similar increase compared to the iPhone 5 would suggest that about 62 million iPhone units will be shipped in the December quarter. They think that’s probably above expectations, noting that the China lunch is being delayed.

In addition, they believe that it’s possible consumers are simply more aware that they can preorder the iPhone, since the number of preorders has been increasing over time anyway.

First weekend shipments might disappoint

The Bernstein team does warn investors that Apple could disappoint with first weekend shipments, however. They’re not sure that the number of shipments for the iPhone 6 and iPhone 6 Plus will beat the 9 million iPhone 5S and iPhone 5C shipments Apple saw last year.

They note that the company’s preorder announcement and also delayed customer delivery dates suggest that supply constraints compared to demand may be stronger this year. In addition, they point out again that China isn’t a launch country this year. And third, they note that there is no less expensive model, like the iPhone 5C.

As a result, they estimate first weekend shipments to be between 7 million and 8 million units.

Clues from Apple’s statements

The analysts note that in Apple’s press release about the preorders, the company said a “significant amount” of those preorders will be delivered starting on Friday and “throughout September.” They say this looks to be more conservative than last year’s press release, which said “the majority” of preorders would be delivered on the Sept. 21 launch date.

They also say that the shipping times for many of the earliest iPhone 6 orders seem to be a lot later than they were in previous iPhone launches. They point out that Apple’s reported preorders totaled about 40% of first weekend sales for the iPhone 5, 27% for the iPhone 4S and 36% for the iPhone 4. As a result, they think preorders could end up being higher than 40% of Apple’s total first weekend sales. They estimate that preorders could be as much as 50% to 60% of the company’s first weekend sales, particularly because of what Apple said about the number of preorders that are likely to convert into first weekend sales.

Because of these factors, the Bernstein team estimates between 7 million and 8 million iPhones will be solid in the first weekend. That compares to some expectations that could be as high as 10 million units.

Disappointment just a “red herring”

They point out that even if Apple does come up short, they say it’s a “potential red herring” because of Apple’s worse than usual supply constraints. They point out that first weekend sales are mainly an indication of available supply rather than demand.

In addition, they say that a slower ramp could be better for Apple, as rolling the iPhone 6 and 6 Plus out in China later will help push some sales into the March quarter. That would help to smooth off the usual seasonal slowness of that quarter.