Summer in the Swiss Alps means green valleys, melting glaciers, and hiking trails that stay open well into September. Booking in late winter gives you the best shot at decent train passes and alpine lodges before the summer rush prices everything out.
A typical two-week trip runs about $4500 once you factor in flights, mountain trains, and Swiss cheese. Spreading that out over a few months helps keep your everyday cash flow intact while you secure the reservations you need.
That 0% window is a hard deadline, not free money. If you still have a balance left when the 15 months are up, the standard interest rate kicks in on what you owe.