Unfortunately, there is nothing standard and no way to know. I've known players with seemingly major concussions who have bounced back 100% almost immediately (before the recent protocol of waiting for at least some period of time) and I've known players with seemingly minor concussions who, five months later, still could not ride a stationary bike for more than 5 minutes without feeling nauseous and dizzy. With this being his third or fourth concussion (not sure, but I know it's not his first), the chances are greater that it could be an extended period and that it could happen again quickly if he comes back too soon. Concussions can end careers, which is why they are now often referred to as "brain injuries." I'm sure that the athletic trainer is testing him daily and will clear him when he is ready. But there is no way to project his return based on past experience. Each instance is unique.