Norway in May or September gives you long days, quiet fjords, and lower prices before peak summer crowds show up. You get crisp air and green landscapes without fighting thousands of tourists for a view of the water.
A solid trip usually runs around $3,500 for flights, stays, and train tickets. Spreading that cost out over time makes the upfront hit a lot easier on your bank account.
Remember that an intro window is a deadline, not free money. If you still carry a balance when the 18 months end, standard interest kicks in on whatever is left, making your trip more expensive in the long run.