I'm not an expert and it really depends on where you are starting from in terms of age, health, weight, etc. I've also been doing this for so long that I can't remember what my starting program was like.
In general, I would say to take it slow and see how you feel. If you feel good, then gradually increase the distance. If you don't feel good, then decrease the distance.
Also remember that the older we get, the more slowly we need to increase the intensity. That's a problem that I've been having lately. I have a 30 year old mind in a 47 year old body. Injuries happen lots easier as we age.
I hope this helps.