Time between landing/customs and boarding train at Zurich airport?

Typically how long does it take to get through customs (we will have
checked bags).

For passport control, it depends on how many flights are arrving at the same time. Most times, it’s taken me 15 minutes or less, but this past March it took over 90 minutes.

While the rail station is inside the airport, it can still take some time to walk there from the gates. But there is no need to book that in advance. Just go to the station whenever you're done, and there will be a train every so often. Some are direct (no change) to Luzern, and other options where you do have to change at Zurich HBF. Easy.

The Luzern-Interlaken Express (part of the Golden Pass route) does not take reservations, so just go to Luzern and take the next train to Interlaken once you arrive. There is a train every hour. If you want to upgrade to 1st class for that train, you can do i at Luzern station.

Golden pass from Lucerne to Interalaken does take reservations for both 1st and 2nd class and as of now, if seems like there are only 12 seats left on the train that I think we can make but again, I am not sure if what to do if we miss the timing. I am going to call them tomorrow when they open to ask.
I am looking on this website for information:
https://shop.luzern.com/en/stories/luzern-interlaken-express

You do not need reservations for the Luzern to Interlaken train. Just get on in Luzern and find a free seat. This is a normal service train.

if you miss the train from Luzern to Interlaken Ost via Brünig just go back into the main concourse and find a place that appeals and have a coffee. There will be another in an hour.

Are you madly trying to get to a named train? The scenery is the same and the stops are the same and every train has tinted panoramic windows. The view is spectacular. Sit on the right hand side leaving Luzern. When the train turns around at Meiringen stay on the same side (now the left side) but turn around as those going forward will now be going backward.

Just be sure it is the Brünig route. Enjoy the cogwheel climbs and descents. Leaves from Luzern platform 13 (almost always - because of the narrow gauge) at 6 minutes past every hour.

The route through the Emmental (yes, where the cheese comes from) and Bern is slower and all flatland.

It's never taken us more than 15 minutes to clear Passport Control in Zurich. I believe Carrie's last trip was during ski season, and she got caught in the weekend rush to the slopes. However, I have never had checked bags, so I don't even know where Baggage Claim is, or how fast.
Based on the post- COVID airline chaos and strikes, I think you have a greater chance of delayed/ canceled flights causing you to miss a designated train. At least, that has been my experience flying in the past few years.
Good luck, and have a wonderful trip in the beautiful country!

All the trains on the Luzern - Interlaken route are the same. They are nice trains, with big windows, but for most people that use them they are just a means to get around. Do you expect kids going to school, commuters going to work, people going shopping, or on a hike to reserve? Swiss do not reserve seats on trains.

Because there are tourist that like to reserve seats and the railway isn't going to turn down an opportunity to make some money you can indeed reserve seats on those trains. They cost 14,- a piece which I personally consider downright highway robbery...
But they will only reserve seats in 3 cars of the, train, so most of the seats aren't even reservable, and you can expect to have a free seat available somewhere. The train is in summer normally 11 cars long.

So my advice: Do not bother with reservations. Just find the train you want to take and get on. That is how this works in Switzerland.

WengenK,
after reading your post, I am at peace. I have no idea why I was so stressed out!
We will just go with the flow, get out of the airport when we can and once we get to Lucerne, I'll stop by the Tourist Information desk by platform 3 to get help if I still need assistance.
For some reason I was under the impression that reservations are a must!
I am learning as I go and I greatly appreciate all the wonderful advice I receive on this forum!
Thank you everyone!