A patio changes how you use your home, turning a messy yard into an extra room for dinners or coffee. Contractors are usually desperate for work in late autumn, which is the perfect time to get a quote since the rush of summer is over.
You want to pick a design that drains well so you don't end up with puddles near your foundation. Getting three separate quotes is the only way to know if you are being overcharged for labor or materials.
That 0% window is a hard deadline, not a gift. If you still have a balance once the 18 months are up, the interest charges will kick in, which can quickly wipe out any savings you gained from off-season pricing.