You want your car to stay looking clean without a patchwork of stone chips ruining the front end every time you hit the highway. Keeping a daily driver in good shape means paying for upkeep that actually preserves the body, and a clear film kit for the high-impact areas does just that. Late autumn is the right time to book this because body shops hit a slow patch before winter and have open bays ready for detailed work.
When you talk to the shop, negotiate the install price and the film coverage first before you mention how you plan to pay. A financing window is for spreading out the cash flow, not for getting a discount on the labor.
Just remember that the intro window is a hard deadline, not free money. If you still carry a balance when those 18 months are up, interest hits on the remaining amount.