Hi, Just started my very first build with an ST-12, I find the online ST manual and YT vids to be very vague concerning this particular bridge and stringing procedure, not really helped very much by all 12 strings being unmarked and difficult to decide which are the octave strings.
If you only have the kit strings that came in a clear plastic wallet, then I'd only use them for initial basic setting up and checking neck straightness (if at all). They really are bad strings and not at all good quality. I'd buy a set of your normal brand of strings and use those. The 6-string kits come with a free set of Ernie Balls, which gets around the poor quality string issue, but unfortunately the 12-string and bass kits don't.