I'm not sure how old/large your snake is, but myself, I wouldn't ever feed mice. I've heard a lot of stories about snakes acquiring a taste for mice and becoming very difficult to get switched over to rats. Mice won't be large enough food items for very long and you'll have to switch to rats, anyway. So, why not just start off with rats? Just my opinion...
I am so glad my snakes have never listened to the "story's" or read the "rule book" on what they can and can't eat. If they had they never could survive in the wild. "Darn, I can't eat that because I read once I may become addicted.....guess I will just starve".