I dont mean to be an ass, but if you are running an 8 minute mile (for just one mile), you are pretty out of shape and don't want to start real big. Just start with 2 miles a couple days and see how you feel, just to get to know your body and whatnot, then you can start to gauge for yourself how far you want to go. Also, be sure to have good shoes, drink plenty, and stretch before and afterwards. Ive made the mistake of not stretching after soccer and it comes back to bite you in the ass the next morning. I would recommend doing a cool down the last quarter mile and then stretch for 10 mins when you are done and then stretch again in 40 mins.
thats about all from here