If the car is nonconforming, you must tell the dealer about it within a reasonable time. A “reasonable time” is not defined. It will depend on your circumstances so don’t wait. Tell the dealer you want your money back as soon as you can because the Court does not stop the clock, “time”, until you tell the dealer there is a problem with the car. Putting it in writing is even better. Keep a copy for your records. You must also tell the dealer about the problem before there is a “substantial change” in the car. There are plenty of things that could be a “substantial change” in a car. Think of it this way. You may not be able to return the car if you wreck it so don’t wait.
Remember this is not legal advice. There are lots of scenarios that can change how to approach this situation. Sit down with an attorney to discuss your options and how your situation fits with the law.