In regards to adding that extra day or not:
Well it comes down to what loop said. Anyone can run a 5k, it isn’t that physically demanding in all honesty and I am sure that if you haven’t run more than a mile in your life, than yes, it might seem like a feat in and of itself, but if you are going to put some effort in, don’t go half ass!
I would definitely up your mileage but lets not set your goals quite where loop has them, not yet at least. If your best mile is a 7:42, we should aim for a 5k in the low twenties. If you can’t run a mile under 6 minutes, I for one am not going to push you to run three six minute miles. No, as it is now, I would be happy for you to bring your miles down to 7’s which would put you just over 21. PM loop and talk runs with him if you want, but I would make a low 20’s (eh, less than 24?) your prioity for the first two weeks and we’ll see how that comes along. Btw, do you know the terrain of the run yet? If it is hills, you should definetly put in some hill work, its great fun, but if it is relatively flat, you can just train straight. It sounds like you are in need of general conditioning right now and not fine tuning really so perhaps the track work would be better off later down the line?
The best advice I can give you for now would be this. At least twice a week, run 4-6 miles and don’t stop. Also, unless you are really unconditioned, you should be able to do each mile under ten. If you have never run more than a mile, you will wish for a quick and painless death but I assure you that running four-six miles isn’t near as bad as you think it is; yes, you will feel like you can’t run anymore and you will want to walk and that is okay, just slow your jog down for a minute or two, but don’t stop. The goal of these days is for your delicate heart to learn the joys of continued elevation. Then once a week, run an agressive 2 mile run and if your mile is at 7:42, you should aim for two miles under 8:30 for now? And once a week, for enterainment, aim for a 3 mile run so you can monitor your progress.
Don’t shaft the 4-6 mile runs because they don’t seem applicable to a 3 mile run, they are a great psychological tool. Run six miles straight for an hour and you won’t think twice about the two mile runs. If 3 miles is the farthest you ahve ever run, it seems long. If you have gone 6, its just a quick run in the park. Best of luck! J