Go out, and run just those few minutes and call it a day. See how you feel the next day and if you dont feel to stiff or sore, add another few minutes. Just add a couple minutes at a time to get back to where you were before.

Hope this helps.
Blake

I was actually worried about the glass too, and that seems to be a common complaint. I have a couple lines of advice on this topic of where to run barefoot.
First, I started by walking barefoot alot around my neighborhood. I would walk on concrete. I also run in my neighborhood for my barefoot runs because the concrete is very smooth, so it allows me to run longer. I have tried running on older asphault, but it ends up being very rough, and all the little rocks on the surface decrease the amount of time I can run at any given time. I personally want to transition fully on concrete because it really makes you pay attention to your stride being the least forgiving surface.
I like running on dirt the most, but there are no real dirt paths where I live. Grass is the next best, and most forgiving, but many people dont like to run on it because they cant see if there is glass.
This is perhaps the biggest complaint. I will stress that I think the optimal way to do it is to run during the day, on concrete/asphalt until you can run for 30-40 minutes/day with no big problems with your soles. At this point, your feet have adapted to where they will be very flexible and also very sensitive to the surface. Not sensitive as in pain, but as in reflexes, you will notice that when you step on sharp rocks your foot will either mold around it or you will pick your foot up very quickly without the same pain as when you started. You will also have a better stride where your foot lightly strikes the ground and doesnt hammer into it like with shoes.
So, all this means that you will be paying more attention to where you are running, avoiding glass, and unless it is a jagged edge of a bottle pointing straight up(which would cut through a shoe too) its not going to do any more damage, and I would argue less damage, than some of the sharper little rocks out there.
Best advice I can give though, run anywhere where you know it to be smooth and family friendly as those places are least likely to have glass broken from partying, and keep that your spot for running until your feet are tough enough to handle the rougher stuff.
last bit-an indoor track might be a good option if the surface is smooth enough, i just cant stand going in circles, I, personally, run because of the freedom it gives me to go anywhere I want to.
Blake