It largely depends on how long it takes the provider to follow through. Many people have been told by their provider that an MEB was being started, but there was no or slow follow up by the provider. In my case, it took months and I was very seriously ill and my condition was definitely going to be unfit.
In my case, the PEBLO's office was located in the same building as my PCM. After being informed that I was being put up for a board, I was directed to visit the office. When I arrived, my doctor had already called the PEBLO so he was expecting me. This is probably the best case scenario, but I wouldn't hesitate to either ask your PCM or contact the office that the PEBLO is located at.