The time scale is different for eveyone.

Because it is doubtful that the headaches were caused directly by the fact that you had amalgam fillings installed but may be caused from the accumulated mercury that was offgassing from the fillings, it's possible that the accumulation of mercury itself is the cause of the headaches. Therefore, the next step is to remove the mercury.

I would recommend that you visit the Mercury/Amalgam forum and ask about methods of chelation to the group there which should help you find out how to remove the mercury from your body.

Also, the body will normally (in most people) begin to be expelled by itself over time. Taking supplements can speed this process, but isn't always necessary for relief of symptoms.