Trains in Switzerland

You can book the same day. Sometimes, routes have supersaver fares with advance purchase.

You might want to look into the Swiss pass that will cover your trains to Wengen
and some cable cars and other great discounts on that region.

Download the Swiss Rail Travel App. Once you’re there, you can easily check routes and timetables to see what is available. It also shows how crowded the train is likely to be. If you set it up, you can buy tickets using the app, or you can buy from machines at the station.

It also shows connecting bus routes.

Depending on how long you’ll be in Switzerland and in the Wengen area, you may want to buy a Swiss Travel Pass or a Half-Fare card. I had a Travel Pass and almost all of the funiculars and cable cars I rode in the Bernese-Oberland region were included (including the ride to the Schilthorn). I got a discount on the few that were not.

For the few days not covered by the Travel Pass, I just bought a ticket at the station shortly before travelling.

I travelled from Zurich to Thun and from Lauterbrunnen to Zurich with no problem buying tickets just before departure. The only really crowded day was from Thun to Zermatt on a sunny Saturday. 2nd class was full with lots of people standing. It was the one time I considered buying a 1st class upgrade.

https://www.sbb.ch/en/timetable/mobile-apps/sbb-mobile.html

All the best,

Raymond

I second Raymond. The SBB App is great. No matter where you are, it will give you all of your SBB travel options from that location. Or plug in your own info.

You do not "book" trains in Switzerland. You buy a ticket, which is valid on any train on the date listed on the ticket. You either buy on the day at the station, or on a previous day, in which case make sure the date on your ticket is correct.
Ticket machines default to the current date, you can change it to a future date.