Prague in November is moody, quiet, and honestly just better than the summer circus. You get the gothic spires of the Old Town and the famous local beer culture without fighting through tour groups every time you turn a corner. Prices drop once the autumn rush clears out.
Spreading out a $2100 trip takes some planning so you are not scrambling when the bills land. We can look at how to break that total down into steady chunks over time.
That intro window is a deadline, not free money. If you still have a balance left when the 15 months are up, standard interest kicks in on what is left over and gets expensive fast.