I set my date for after the holiday because I knew I woild be around alot of people that smoked, and I love to smoke when I go camping. So I set it for after that. I think you need to give youself enough time to prepare and separate.
Be honest with yourself about how long you need to get past your biggest triggers, I chose 3 weeks. I was scared at first too. In fact I had a panic attack when I set my date. I am super excited now, I just can't wait to be done. I thought I would just quit before my date, but I know I need that time to work the program. You are doing great, at least you have a time frame in mind , that is a good first step. You can do it! Be sure not to set your date around any major events happening in your life, its too hard to quit smoking under too much stress.