transit from plane to train in Zurich

Last time I went with United to Zurich (August) it took maybe 15 minutes, but I was sitting up front, , the plane was rather empty, I had no checked luggage and a machine readable EU passport.

If you just want to take the local train (S-Bahn) to Zurich, you can buy the ticket when you are ready. There are machines or you can download an app up front. The machines take regulars credit cards.

Buying a ticket for a specific departure time is tricky and comes down to a risk assessment. Factors involved are

1. Does your flight come in early, on-time or late? Their are website that run statistics for specific flights but there is still a fair bit of variation
2. How full is the flight and how long will it take you to deplane
3. Jet bridge or bus? Chances are very high it's a jet bridge for a United flight from the US, but you never know
4. What's your passport? How long is the line?
5. Are there extra Covid checks and document controls? Do you have the SwissCovid app or an EU vaccination certificate?
6. How much luggage have you checked and when will it come out? Priority can help here, but it's also often ignored at European airports.
7. How long does it take you to get from gate to customs and onwards to the train station. That's a bit of a hike. Chances are you are coming into Terminal E and have to take the Skymetro to the main airport. The train station is in the airport center. The train station is downstairs, the tram station is upstairs, so make sure you know which one are you taking. The local trains to Zurich leave from downstairs.

A recommendation would depend a lot on your passport, luggage situation and Covid documentation. I would probably budget at least 90 minutes and 2 hours is safer. Depends also on the price of the ticket: you need to balance more waiting against having to potentially pay more. This may be a case where flex ticket is the most convenient option.