I do not think there is going to be and absolute answer for you that will guarantee that if you start back up you wil not have to back off. However, I think you will know when to start when the symptoms of over training are no longer there and you start with the less stersfull exercises and do then for 5, 10 minutes and build as long as the symptoms are not there.
Now what you also have to look at is what else are you doing besides training to cause over training sysmptoms. Sleep, nutrition, hydration, stress in life etc. All of these can also affect your adrenal system.