Why a 15M iPhone 5 order placed now makes sense

Apple (s aapl) has reportedly placed an order for 15 million next-generation iPhones with supplier Pegatron, according to DigiTimes. While Apple obviously isn’t commenting, a big order now makes sense for a number of reasons, not the least of which is Apple’s change from its traditional new hardware announcement during the June developer event.

DigiTimes gets its information from sources within Apple’s supply chain, and though it has a mixed track record when it comes to the accuracy of its reports, it does tend to do much better when dealing with the suppliers that win device manufacturing contracts. A fall launch for the next iPhone, and September in particular, has long been rumored and repeated in various reports, and placing an order now, just a couple of months ahead of such time, is definitely in keeping with how Apple’s supply chain works.

The 15 million units is a bit high for a launch order, but there are a number of factors that could contribute to Apple needing a larger than usual initial stock pool. First, Apple could be planning to launch the next iPhone in more markets simultaneously. The U.S. remains its largest market, and also one that still showed 155 percent growth last quarter, but iPhone growth in China is exploding, and if trends continue, Apple’s biggest business will be soon be overseas. A simultaneous worldwide release could better capitalize on the iPhone’s success in emerging markets, especially timed as it just in advance of holiday shopping.

Apple also has to expect, as Verizon (s vz) clearly does, that a new iPhone available simultaneously on the two biggest U.S. carriers will create more demand that previous iPhones have. While the Verizon iPhone 4 launch didn’t exactly draw huge crowds, the phone still appears to have sold well by recent estimates, despite it being technology that’s nearly a year old in a market where hardware is fast improving.

Also consider that more existing iPhone customers than usual might be eligible for a hardware upgrade when the iPhone 5 arrives. In the U.K. especially, customers who purchased the iPhone 4 on an 18-month contract will be ready for new hardware come September. If more people are eligible for special pricing, then it stands to reason there could be higher than usual demand for launch-day stock, and Apple has already had plenty of trouble meeting demand in the past as it is.

At this point, it’s just a matter of fine-tuning when we can expect to see a new iPhone, not if it’s coming. More and more, signs are pointing to September, so we won’t have to wait long to find out for sure.