Well basically once you've milked it for everything it's worth. But just monitor yourself and play it by ear.
You know sometimes I think people are to "plan" oriented when it's better to be "reaction" oriented. Changing programs is not like changing the oil in your car where you do it once every so many miles whether needed or not. Better to make small changes to what your are doing to further sustain progress.
You've made one change only so far and you are planning another so it's better to just wait and see....of course I can't predict exactly how long you can do it or how long you will even want to