It's completely up to you. Follow what your body is telling you. If you run in the morning and at night you're still pumped with energy and your body feels good, go for it. Every other day is perfect because you allow your muscles to heal in the meantime. If you run too much like every single day, you'll have knee problems and develop shin splints which are excruciating. I lifted weights all my life for football and stuff and resting your body is just as important as exercise, if not more so.
You and I are kinda large people...I've always had a large frame so running put tremendous strain and impact on my joints and back. In fact, right before I left the military I had to stop running and go to physical therapy because I have a muscle in my back that gets inflamed if I do a lot of high impact exercise. It just built up over the years. Running is a very high impact sport and if you're not a natural runner, you can seriously injure yourself if you overdo it.
However, there is something you can do that will help you tremendously and it takes no more than a minute to do. If you find yourself standing around by yourself with nothing to do, throw up like 30 push-ups really quickly. Do this multiple times during the day. If you're watching tv and a commercial comes on, throw up some push-ups and sit-ups until your program comes back on. It's not going to hurt you and will only help you. Your arms will be like boulders and your upper body strength will improve ten-fold relatively quickly. If you're sitting around on your break at work, knock out 30 push-ups. After about a week, up the number to 40. After a couple of months, you'll be doing like 100 push-ups in about two minutes. It also helps with your breathing and lung capacity. What you're doing is putting your body in a constant state of tension; not overly so and not more than it can handle, but you're accomplishing two things. First, you're getting in shape, and secondly you're immersing your entire lifestyle into fitness. After a while it will become a habit and you won't even notice it.
I'd run three times a week for a mile each time if I were you. If you feel like you can do more, then do it but don't overexert yourself. After a month or so, your body should be getting used to all the running, push-ups, and sit-ups and you can up the distance you run or number of push-ups. Once your body gets used to having this strain put on it every day and can handle it, that's when you really start pushing it. That's when you start sprinting a lap, jogging a lap, sprinting a lap, jogging a lap, etc.
Also, one thing to note: you have to complete the distance within the time alotted. If you're able to sprint 1.4 miles in 8 minutes, then you can walk the rest of the way.
One last thing: see if you can find a partner to run with. It's much more fun and you'll start challenging each other to see who can be the fastest and go the farthest once you start really getting into shape.