1st Time to Switzerland and then to Italy

www.sbb.ch is the Swiss National Railway, they can get you to anywhere from anywhere in Switzerland. There are several crossing points from Switzerland to Italy, all going to Milan, which is the Chicago of Italy. You pretty much need to go to Milan to get anywhere in Italy.
Trains make stops along the way, so there is absolutely no reason to go back to Zurich to get to Milan.
From the Berner Oberland, the trains go to Spiez, then to Brig, then to Italy through the Simplon Tunnel.
Late May is a bit early for Gimmelwald. But it all depends on your interests.
Assuming you are landing at Zurich airport, go right from the airport train station to where you want in Switzerland, then to Milan and then to where ever you want in Italy.

There are many beautiful areas in Switzerland; hard to find a place that isn't lovely. But the Bernese Oberland is classic. You can get from the Zurich airport to Lauterbrunnen in less than 3 hours. You'd make a connection in Lauterbrunnen for Gimmelwald and other higher locations. When you're ready to head south, Milan's as close as 3-1/2 hours from Lauterbrunnen if you take the most direct route, which involves changing in Interlaken Ost and Spiez. There are longer routings and some that require more changes.

Swiss transportation is fabulous and runs like--you've got it--clockwork.

I think late May is a fine time for the Lauterbrunen valley, Gimmelwald, Wengen, etc. It's low season so crowds will be down. I once spent a week there in late May and got glorious weather the whole time. While most higher altitude hiking trails will still be closed (and the Allmendhubel line will probably be closed for maintenance), there will still be lots of lower level trails open. Biking in the valley, ferry rides on the lakes, paragliding, trips to the Schilthorn or Jungfraujoch on clear mornings, and the camaraderie at the Mountain Hostel will be in full swing!

Demetrius,
Sorry to say it, but your phrasing implies you do not understand how trains work, especially in Switzerland. Trains (and in a few cases connecting buses) will get you anywhere in Switzerland. You do not have to go somewhere to catch a train, the train runs from where you are.
See the rail map of Switzerland here: https://www.sbb.ch/content/dam/sbb/de/pdf/freizeit-ferien/ferien-kurztrips-schweiz/internationale-gaeste/sts-geltungsbereich.pdf

• "Gimmelwald ..... How do I get to there from Zurich?" - By train of course. But, are you arriving in Zürich or Zürich airport? Two different places, each with their own station. Nearest station is Mürren, which is a short walk to Gimmelwald. Or you can get a bus and then a cable car from Lauterbrunnen station.
• "Should I stay in Zurich overnight on 5/24?" - Why? If you want to go to Gimmelwald, go there, don't hang around in a big city.
• "Since I wlll only be there from 3 to 4 days, where should I set up home base?" - If you want to go to Gimmelwald use that as your base, or somewhere else in the area, like Lauterbrunnen
• "What could I possibly do or what should I do in that amount of time before heading to Italy?" - enjoy the mountains, fresh air and scenery. Perhaps do a few walks and go up to the top of one one cable car. From Gimmelwald or adjacent Mürren the cable car goes up to the Schildhorn.
• "Where should I leave to get to Italy." - from wherever you are.
• "the only direct route by train is from Zurich to Milan. Which means I would have to double back to Zurich" - not so. trains are not like planes, they make intermediate stops and it is designed so that the interconnections nearly are as fast direct trains. You can get from anywhere in Switzerland to Milan. And there are also Basel - Milan trains.

Go to www.sbb.ch enter Gimmelwald to Milano, and a time and a date, and you will find your times. takes about 5 hours.

Demetrius,

Switzerland has an incredibly efficient transportation system, so as the others have mentioned you can get anywhere in relatively short times. A few questions......

• what time does your flight arrive?
• are you planning to stay in Gimmelwald, or one of the other towns in that immediate area (Lauterbrunnen, Mürren)? It's difficult to provide specific directions to your location without having that information.

Rather than wasting a night in Zürich, I'd suggest going directly to the Berner Oberland. There's a rail station right in the Zürich airport and you can buy tickets when you arrive. Travel time to Lauterbrunnen will be about 2H:45M with two or three changes, depending on which train you connect with.

Just to clarify a point mentioned earlier......

"Nearest station is Mürren, which is a short walk to Gimmelwald. Or you can get a bus and then a cable car from Lauterbrunnen station."

If your destination is Gimmelwald, it's far easier to take the Post Bus from the Lauterbrunnen station to Stechelberg, and then the Cable Car to Gimmelwald (the first segment of that trip is steep and spectacular). The trip to Mürren via train involves a short Cable Car ride from Lauterbrunnen to Grütschalp and then a connection to the BLM railway. You don't have to walk down from Mürren to Gimmelwald as you could also take the Cable Car, but that would be an extra expense. That route is not one I'd like to tackle after a long international flight and a ~3 hour train ride.

If you're planning on exploring both sides of the valley, Lauterbrunnen makes the best home base as it's the transportation hub for the area, and both sides are easily reachable from there.

For the trip to Milan, you'll first have to go from Lauterbrunnen to Interlaken Ost (about a 20 minute trip). Train travel time from Interlaken Ost to Milano Centrale ranges from about 3 to 6.5 hours, depending on which departure you use, with 1 to 4 changes. There are numerous departures so you'll need to decide what time you want to leave Interlaken, what time you want to arrive in Milan and how long you want the train journey to be. Note that some of the trains on that route have compulsory seat reservations, which will be provided with your tickets.

Thanks Sam, Acravein, FastEddie and Ken. Your information is extemely helpful.

I absolutely agree with above posts.
The Swiss rail system is a dream!
Do not stay in Zurich if your goal is to get to the Berner Oberland area. It is very easy to get to Lauterbrunnen from the airport, which would be my suggestion for a place to stay, based on your travel plans. We stayed in Interlaken for three nights. Although our B&B was awesome, I would opt for Lauterbrunnen or Murren on our next trip. (Then we stayed in Gimmelwald for three nights. It was incredibly picturesque but a little too sleepy for us.)