If I remember correctly, I think I took 3 zero's over the 750 miles I completed on my first attempt. Only reason for that many was due to a severe sickness with no energy. Went away the next day, but I ended up waiting it out "just in case it came back". The other day was another no energy day, but I think I even went a few miles so technically that would be a nero I guess. Just listen to your body, only you know it. You'll know when you feel like it's time. Enjoy a town or two, that's why they're there and it's part of hiking the trail. Good to take some time off work once in a while.