Apple Inc. (NASDAQ:AAPL)’s launch day for the iPhone 5S and 5C appears to have gone off well in terms of demand, but how much will supply affect the company’s early sales results? Stifel analysts believe that demand data points from the first day of sales were better than expected, but they note that the only thing we don’t know is just how bad the initial supply for the iPhone 5S was.

Apple Inc. AAPL

iPhone demand data positive

Analyst Aaron C. Rakers and the rest of his team believe Apple Inc. (NASDAQ:AAPL) will ship between 6 and 7 million iPhone 5S and 5C handsets during the September quarter. They said there could be upside to 7 million because of “the velocity” of the iPhone launches this year, but they remain “tempered” because of what looks like major supply issues of the iPhone 5S.

Supply of the gold iPhone 5S in particular seemed to be extremely poor, although it didn’t take long for all iPhone 5S models to shift into later and later shipping dates. In their post-launch report, the analysts left their September quarter estimates unchanged at 28.8 million iPhones total, but they said there could be upside to their 47.8 million iPhone estimate for the December quarter, particularly because so many iPhone 5S shipments were shifted into October.

Apple has new iPhone markets

They said there are some important things to keep in mind for this iPhone launch. For example, this will be the first iPhone launch which includes China, Singapore and Puerto Rico. They note that the lack of a deal announcement with China Mobile is a disappointment, but together, China Unicom and China Telecom have 442.2 million mobile subscribers. This is still a large new market available to Apple on launch weekend. Earlier this month, China Unicom alone reported that it had taken preorders of more than 100,000 iPhone 5C handsets over the first three days of the prelaunch.

In addition, this is the first year Apple Inc. (NASDAQ:AAPL)’s new iPhones are available to NTT DoCoMo subscribers. At the end of August, the Japanese carrier had 61.8 million subscribers.

Stifel analysts continue to rate Apple Inc. (NASDAQ:AAPL) as a Buy with a $540 per share price target.