Carl, EMG or no EMG, I am sure you will do fine. From reading your posts, there seems to be no evidence of weakness at all, only a feeling of weakness, which is extremely common and which I have experienced myself.
In answer to the original post, less than a month. You might also ask how many people have had multiple EMGs and continued to worry. After careful consideration, I reasoned that my symptoms fit BFS like a glove, and that if I insisted on worrying that I might be among the very small percentage of people who twitch for a totally different reason, then I might as well worry about lung cancer, a brain tumor, a car accident, or any of the other causes that were equally or more likely to cause my death.
Oh, and the car accident almost happened: