Since there are no preservatives in fresh milled whole wheat bread if leaving it out on the counter, it should be eaten within 4 days.
Refrigerating the bread, can help it to last up to 7 days, but this can cause the bread to be a bit dry.
The best recommendation is to take out the slices you will need for each day and keep the rest in the freezer until needed. You may use a butter knife to easily separate the slices once frozen.