One day or Day one

I’ve been putting off quitting for 6 months now. My excuse was getting a job or getting accepted into a program, but I am now at the highest point of my life in terms of success, I know I need to quit. I’ve tried before and my longest was 10 days, and I only relapsed because I was stressed about the upcoming semester, but now that I’ve seen success and have a free summer, I am going to quit. Any advice for the potential increase in appetite tho?