に先立って => before; prior to ~ N2
別に~ない => not really, not particularly N3
に[先立「さきだ」]って/に[先立「さきだ」]ち/に[先立「さきだ」]つ => Before A occurs/takes place N2
Time, Situation
は別として => aside from; apart from; except for; whether or not N3