Bob is probably about right when he suggests nothing arduous within a month so you could make the OCT your last long day out and be pretty confident you would be recovered.

I did two BGRs 7 weeks apart so a month to recover from OCT should be enough but you will know better that anyone else how you feel. If you want to know why I did two (or you can't sleep properly) have a look at http://www.iwcs.blogspot.com/