I'm going to look for another job after the holiday season.
Oh really? Why do you want another job?
I need to try something new.
It's okay to want to find something that makes you happy. It's acceptable to search for another job before you leave your current one. It will make you look good that you didn't just quit in the busy season.
My manager is a dickhead. I hate him.
I'm sorry that your manager is mean to you. It sounds like you definitely should start looking for a new job then.