に先立って => before; prior to ~ N2
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
おもったら => just when; no sooner than ~ N2
Things do not match the prediction
~からとおもって => Because I think... N1
Base, base
(か)とおもうと / (か)とおもったら => just when; no sooner than ~ N2
Simultaneously
…とばかりおもっていた => Thought that ... N3
Speculation
…ものとおもっていた => Thought it was... N2
Vague
に先駆けて => prior to; to be the first (pioneer); being ahead of ~ N1
お => Prefix N5
Respectful, humble
まさか...とはおもわなかった => never thought that N3
Surprised
...どおし => Throughout N3
Continuous
とおり => Several ways N4
Means and methods