Having done couch to 5k, it was great for me, but a few weeks in, the idea if running for 10 minutes ws terrifying. If you can already do that, then I reckon you're most of the way to 5k already. You could always skip ahead to the point that the program is doing run10, walk 2, run 10, walk 1, run 10 (or something like that, they're all different) - somewhere around week 5-6 probably. You could just start there.
On the other hand, if you're okay just adding a couple of minutes every time, then just do that.