>> Day1 --> check into hotel, lunch ... If the day is great, then go to Shilthorn. If not then go for a boat ride and Ballenberg museum.
The Schilthorn cable car will be operating, but the Ballenberg Open-Air Museum is closed for the winter, and doesn't reopen until 14 Apr 2018.
As the Schilthorn is on the opposite side of the Lauterbrunnen Valley from where you are staying, you could save time by leaving your luggage in the lockers at Lauterbrunnen and going to the Schilthorn before going to Wengen and checking into your hotel. If you go to Wengen first, it will take you another hour-and-a-half travel time to get to the Schilthorn from Wengen.
That is on top of the time it will take you to get to Wengen and check in to your hotel. Your hotel will probably pick you and your luggage up from the station on arrival, but it is likely you will have to walk back to the station for your trip to the Schilthorn, and all that time will add up to less time to enjoy the Schilthorn (and Mürren) before sunset at around 19:46. Incidentally, 25 March is when daylight saving starts, and clocks go forward an hour - but that will have happened before you land in Zürich.
You can check the webcams for visibility on top of the Schilthorn and the mid-station Birg before going up. However, even if the visibility is not the best, it is a free trip with the Swiss Travel Pass in 2018 - so it might be worth a ride in the cable car, and a look around inside the building on top in any case, especially if the weather forecast suggests the clouds might clear at some stage.
There's also a new "Skyline Snow Experience Park" at the mid-station Birg, which has opened this winter for the first time.
schilthorn.ch/en/Info/ Birg_2677_m_._8783_ft# skyline_snow_experienc e
>> Day2--> if day is great go up Jungfrau and on tye way bacl stop in Kleine Schiedegg.
You can check the webcams to see what conditions are like before buying a ticket to go up:
>> Day 3 --> day trip to Lucerne to enjoy the town.
These suggestions for walking tour routes might be useful:
The "City Guide" PDF on the page below has a map with a self-guided walking tour marked. It's across two pages, so viewing the PDF in "Two Page View" makes it easier to see.
Frommers also has directions for a walking tour:
www.frommers.com/desti nations/lucerne/walkin g-tours
>> Day 4--> day trip to cheese and chocolate factory.
Do you mean those in Gruyères and Broc? Travelling by the fastest route, it would take you around 3.5 hours each way, plus about half-an-hour to travel between the chocolate and cheese factories. Then on top of that is the amount of time you wish to spend at each place.
There's a late afternoon chocolate show in Interlaken: