IVIG/recovery time

I just had a visit with my neurologist and they ran emg tests which showed the arms to be just about normal and the legs still wanting somewhat. Scheduled to revisit at the end of May.
He said that you have to hit bottom before recovery will start and even if IVIG is given before hitting bottom, you will still hit it. I don`t quite understand that. (what is the point IVIG then) But anecdotally, my own recovery seems faster this time and I am quite sure that the IVIG was started at a slightly earlier stage this time.
Ray