Personally, C25K did not work for me, but I started from a very bad place and couldn't do the first lesson. C25K does recommend you go back to prior lessons and work up again if you're doing too much too soon, so if you can manage the first lesson and can listen to your body more than your pride, it can work for you.

Personally, I found the Maffletone 180 formula with a heart rate monitor and time-bounded workouts a better fit: http://philmaffetone.com/180-formula If you are stressed your heart rate will go up, so this is a very good measure of the appropriateness of your current training intensity. Make sure to use a heart rate monitor with zone alarms.

I would do the shift to barefoot separately from C25K. When I went minimalist, I took it very slow, and I actually have pretty strong feet to begin with, from a childhood with summers spent 90% barefoot. I had been pounding my heels in regular footwear (and giving myself sciatic pain as a result) so my first step was to start altering my gait in regular footwear. After a month or two of shortening my stride and being conscious of heel-pounding, I got a pair of minimalist shoes. I gradually wore them more often; at the same time I was barefoot a lot around the yard. Winter put a stop to the minimalist footwear for a while, but I went back to them in spring and have since found minimalist solutions for winter (mostly). I didn't even consider running in the minimalist shoes until I'd been primarily minimalist for a year - it took me that long to entirely modify my walking gait. I've done C25K, in minimalist shoes, and found it very useful, but I would recommend spending at least a few months walking a lot in minimalist footwear to make sure you won't hurt yourself. Walk on as many different surfaces as possible (especially uneven ones) to strengthen the many muscles in the foot, ankle, and leg that you'll need for shock absorption and stability. The time needed depends entirely on you, so as the other poster says, listen to your body.