IMHO there is nothing wrong with a single BOR for T-2-1 if the youth finished a Tenderfoot requirement last. We tell the boys that they can work on all of the T-2-1 requirements in any order (or at least we should!), why should we not expect some of them to do things backwards?
I also recently read that the BOR should be made available when a youth is ready and requests it. (I think it was on http://www.scouting.org/boyscouts/resources/mbc/rank.html but the URL is currently giving an error)
This implies that having scheduled BOR's may violate the guidelines (and will certainly delay a youth's BOR)