Naples to Pompeii - will I make my tour?

You could be OK as long as you can call the tour guide and let them you will be late-will they actually wait for you?

Where are you coming from? Rome?
There are several trains each hour I would take an earlier train and try to make that 9:17 ( or earlier) Circumvesuviana
Those trains are famous for running late
You need to get downstairs to the Garibaldi station and purchase your ticket ( unless there is now tap and pay)

Pompeii Scavi station is really close to entrance

Pompeii Scavi station is really close to entrance

The station is close to AN entrance. We didn't use Walks of Italy, but the tour company we used had us meet at an entrance further south than the one near the station. I'd confirm the meeting point. And yes, 4 minutes is tight. The Circumvesuviana train is one floor level down and then at the end of a long hallway. 4 minutes to catch the 9:17 isn't realistic.

This won't work.
Our tour guide also had us meet further away from the main entrance, probably to get away from the crowds, and it's a longer walk.
Trains - or most modes of transportation- south of Naples use schedules as more of a suggestion. Don't count on anything running on time. Take an earlier train into Naples.
Have a great trip!

Thank you for your help so far. I see I can also take Italia Rail, do you know if that drops us off at the same location?

The Trenitalia tracks are in modern Pompeii city. The closest stop is about 0.75 miles from the Amfiteatro entrance to Pompeii Scavi. This is visible on Google Maps. Not every train stops there, I think. Are you using the official rail website?

Italia Rail is not a train company and operates zero trains

You need to arrive into Napoli Centrale much earlier.
It’s a very big and busy station and there will be many people all around.
You need to find the signs directing you to the lower level where the trains to Pompeii Scavi ,on the Circumvesuviana line , leave from.
The ticket windows are always very busy for these trains.
I would give yourselves at least 45 minutes to orientate yourselves and find your way to get the tickets and then down to the platforms.
Keep your valuables close!

There are suggestions on this newsboard, but IMHO not definitive actual observations, that the Circumvesuviana is installing Tap And Go ticketing for touchless credit cards. I find that hard to believe, but multiple posters have said so. That would eliminate the need to wait in line, but because there are "Zones", you may (??) have to Tap Out in your destination station.

Even in Germany, you can no longer set your watch by train arrivals. That would go Double for Southern Italy!

The Circumvesuviana stops diagonally across the street from the Porta Marina entrance to Pompeii Scavi.

Plan to eat lunch in the cafeteria inside Pompeii, since you cannot re-enter the site with a Same-Day ticket.

You have to do your own research, but at the official site, https://www.trenitalia.com/it.html, it appears that no Frecciarossa stops at the modern Pompeii stations, you would have to wait for a local train. That makes all the trips over two hours, some much worse than that.

Our train arrives in Naples at 9:13

I see I can also take Italia Rail,

It is unclear if you have already purchased train tix?
As above Italia Rail is a reseller- does not operate any trains.
You need a fast train from Rome to Naples then Circumvesuviana from Naples to Pompeii.

Solution to be sure you make the tour is to get to Naples earlier than a 9:13 arrival.

There are multiple fast trains every hour from Rome to Naples on either
Trenitalia- the official train company
https://www.trenitalia.com/content/tcom/en.html
or
ItaloTreno- private company runs fast trains only.
https://www.italotreno.com/en

Both have easy to use apps.

I would aim to arrive in Naples by 8:30ish- that should allow you to catch the 9:17 Circumvesuviana