I don't think you have to (or should) report anything until you feel well enough to attempt to go back to work with the "Ticket to Work."

If you can't reasonably schedule xxx hours per week to work, you are still disabled. You don't have to notify them about minor changes. Most of us have good days and bad days and that's okay. A significant improvement to where you felt confident about working for a few hours each day several days a week would warrent reporting.

I understand they frequently do reviews at the 3 or 7 year mark, but even waive those for older SSDI recipients.