With the iPhone X launching more than a month after Apple's (AAPL -1.49%) typical new iPhone releases, there was good reason for investors to believe production of the device could fail to ramp up on time for sufficient availability before Christmas. But with Christmas now only two weeks away, it's looking like it's easy for customers get their hands on an iPhone before Dec. 25.

As ship times continue to improve for the iPhone X, this adds to a growing list of reasons to expect a huge holiday quarter from the tech giant. Here's a look at iPhone X availability ahead of Christmas and what this means for Apple's holiday quarter.

Customers holding new iPhone X devices on launch day

Image source: Apple.https://www.apple.com/newsroom/2017/11/iphone-x-arriving-in-stores-around-the-world/

Get an iPhone X in just a few days

Since the iPhone X's first deliveries on Nov. 3, production has improved rapidly. Going into December, estimated shipping times for new iPhone X orders on Apple's website in the U.S. was about one week -- dramatically better than estimated shipping times of three to four weeks when the iPhone X was first launched.

Now it has nearly caught up to demand in many markets. As of Monday, most versions of the device can be delivered within two to four days of an online order in the U.S. This impressive availability for the iPhone X remains the same in several other counties, according to MacRumors.

In-store availability of the iPhone X is even better, with many versions available to buy at Apple Stores immediately.

This obviously bodes well for Apple's production ramp-up of the new iPhone X, suggesting initial concerns about production constraints proved to be more speculative than thought. CEO Tim Cook has previously warned investors about relying on speculative reports about the company's iPhone supply chain, saying that given how far-reaching its production network has become, these reports are "not a great proxy for what's going on." But the later-than-usual launch for the iPhone X and an unusually large number of reports about production constraints made this warning difficult to adhere to this time around.

Could this be a demand problem?

There's always a chance that demand, not production, could be the reason shipping times for the new phone are improving so rapidly. But the chances of this being the case are extremely low.

Apple customers holding the iPhone X on launch day

Image source: Apple.

Apple has commented bullishly on demand for its new iPhones on several occasions. For instance, Cook said he was "thrilled" with customer response to the iPhone 8 and 8 Plus on the weekend the two devices started being delivered to customers. And in the Nov. 2 earnings call, Cook said iPhone X orders were "very strong for both direct customers and for our channel partners..." Knowing investors are dissecting his every word, comments about demand like this are not phrases a CEO of the world's largest company is going to throw around lightly.

But the best reason of all to be bullish on the iPhone X, of course, is Apple's guidance for record revenue during the holiday quarter (its first fiscal quarter of 2018). Management said it expected first-quarter revenue between $84 billion and $87 billion, up from record revenue of $78.4 billion in the first fiscal quarter of 2017.

As management said in its fourth-quarter conference call, its guidance is the best indicator of what to expect from the iPhone. "We've put our best estimate into the guidance. You can see from the guidance that we're very bullish," Cook said when pressed about the supply demand balance for the iPhone during the quarter.