anytime. heat the A arm around where it passes through. Not the ball. Use anti seize or something upon installation of new after cleaning the hole. If you paint the A arm, the paint has its thickness and will make it harder to install. Ive used a vice to hold A arm but have heard that leaving it in the car to hold it while removing ball joint is a way. Dunno where I heard that. It will take a good amount of coaxing. A cheater bar might be in your future unless you have a 3/4 drive breaker. I believe the socket you are going to purchase is 3/4 drive.