If you just abandon a Leach field or septic field its a minimum of two years to eat raw root crops, and 1 year for Vegs as long as you keep 2" of mulch between the tops of the plants and the ground. I am seeing a lot of different times , some say a season, some say two years minimum.
Unless there is some pretty exceptional chemical down there, I would feel comfortable planting the fruit trees right away–with some good gloves and washing my hands at the end of the day. Human parasites are not going to slide up the vascular system of the tree into the fruit.Root vegetables and ground-lying veggies that will be eaten raw and can have mud kicked on them are another story. As B Mendelzon points out here, there are many different stories about how long things human waste has to lay fallow. Over most of the US, the legal time for humanure compost is generally taken to be a year.