On Nov. 2, Apple (NASDAQ:AAPL) is expected to report results from its fiscal fourth quarter (which ends in September) and offer financial guidance for its 2018 first fiscal quarter (which ends in December).

Three Apple iPhones showing different sections of the Apple App Store.

Image source: Apple.

I don't think that Apple's fourth-quarter results will be all that important. The period will include only a few days' worth of iPhone 8 and iPhone 8 Plus shipments and won't include any initial iPhone X shipments.

The numbers that would matter, then, are the ones that Apple provides as guidance for the first fiscal quarter. Here are three metrics that investors should take a close look at.

Will Apple deliver significant revenue growth?

Apple's revenue guidance for the first fiscal quarter should convey the kind of demand that Apple is seeing for the iPhone 8 and iPhone 8 Plus, as well as provide insight into how many iPhone X devices Apple expects to ship during the quarter.

To be clear, Apple is expected to be supply-constrained on iPhone X over the course of its first fiscal quarter, so the guidance will reflect iPhone 8 and iPhone 8 Plus demand, as well as how many of the hotly anticipated iPhone X smartphones Apple expects to get out the door during the quarter.

Analysts, on average, expect Apple to generate $85.91 billion in revenue during its first fiscal quarter, which would represent year-over-year growth of 9.7%. The range of expectations is quite wide, though, with the low estimate sitting at $78.15 billion and the high estimate coming in at a whopping $100.29 billion.

If Apple guides for revenue at or above the midpoint of analyst expectations, that could push the shares higher. If Apple misses expectations, investors, rather than panic immediately, should probably look to the commentary that management provides on the call as to why its guidance fell short.

How about gross profit margin trends?

There has been a lot of talk about the potential manufacturing costs of Apple's iPhone 8, iPhone 8 Plus, and especially the iPhone X. In fact, there have been some worries that the iPhone X will be so expensive to build that, as my fellow Foolish colleague Evan Niu explained, even at a high price point, the device could carry a lower gross profit margin percentage than either the iPhone 8 or iPhone 8 Plus.

Any potential gross profit margin impact -- positive or negative -- from the iPhone X won't be felt in Apple's fiscal fourth quarter, so, once again, you'll have to skip straight to Apple's gross profit margin percentage guidance for the fiscal first quarter.

Apple's gross profit margin in the first quarter of fiscal 2017 was around 38.5%, so any significant deviation from that figure in Apple's guidance will certainly be worth digging further into. Apple management will probably address the key drivers of its margin guidance on the accompanying conference call, which I'll be covering in detail.

iPhone upgrade rates

The final metric is the percentage of the iPhone installed base that has upgraded to new iPhones.

Unfortunately, Apple doesn't publish this metric in its earnings results or regulatory filings, but when analysts bring it up on the earnings call, Apple management usually provides some qualitative guidance around it.

Apple will probably have a better idea of how upgrade rates will ultimately shape up during the iPhone 8/8 Plus/X product cycle once it has one or two full quarters' worth of results in, but it surely has its own internal projections already.

Essentially, what I'd like to hear from Apple management is the answer to the following question: Does Apple expect the percentage of the current iPhone installed base that will upgrade to new devices to increase, decrease, or stay roughly the same as it was last year?

Now, the answer to this will almost certainly be "increase," but any indication of how large the increase will be would certainly be helpful.

Ashraf Eassa has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has the following options: long January 2020 $150 calls on Apple and short January 2020 $155 calls on Apple. The Motley Fool has a disclosure policy.