The first three issues of X-Men: The Hidden Years (XHY) have arrived, so I'm going to leave X1C alone for a few days (this is a good time to do it since we've just finished 2007) and go through those.
I think then that it's worth briefly considering how to deal with the title. As most people reading this blog will know, there is a five year publication gap in-between UXM #66, and Giant-Size X-Men #1 which relaunched the franchise in 1975. XHY was an attempt to fill that gap. Indeed, since the issue following Giant-Size... was labelled UXM #94 , it makes sense to consider XHY #1 to #22 (which is as far as it got before Quesada cancelled the series in 2001) as being the "real" UXM #67 to #88.
This is the plan, then: we'll pretend these 22 issues stretch from 1970 to 1972, and calculate the compression constant and Iceman age approximator accordingly. As usual, we start tomorrow at 8am.
 Well, OK, that's not strictly true: the adjective "Uncanny" hadn't shown up yet. Still, UXM #94 is how it is now known.