Good multi-room audio is an investment that should last a decade. We want speakers that talk to each other without lag. Buy into a system that supports regular software updates so you aren't replacing hardware in three years. Buying once is cheaper than buying twice.
Wait for November. Tech brands usually refresh their lineup in late summer or early fall. When the new versions drop, the previous generation—which still sounds incredible—gets steep discounts during Black Friday bundles.
This window is a tool, not a gift. If you still have a balance after the 18 months, the standard interest rate kicks in on whatever is left. Pay it off before that clock runs out.