〜に先立って
Prior to 〜に先立って
Meaning
"Prior to ~", "in advance of ~" — a preliminary step before a major event.
Formation
[verb dictionary] + に先立って · [noun] + に先立って （〜に先立ち / 〜に先立つ + noun）
Notes
Where 前に is neutral about scale, 先立って implies the coming event is significant and this is the groundwork laid for it: a rehearsal before a ceremony, a briefing before construction. It is written-register and takes no personal trivia.
Examples
開会式（かいかいしき）に先立（さきだ）って、リハーサルをします。
A rehearsal will be held prior to the opening ceremony.
Breakdown
旅行（りょこう）に先立（さきだ）ち、パスポートの期限（きげん）を確認（かくにん）した。
Ahead of the trip, I checked the expiry date on my passport.
Breakdown
工事（こうじ）を始（はじ）めるに先立（さきだ）って、住民（じゅうみん）に説明（せつめい）しました。
Before starting construction, we briefed the residents.
Breakdown
発表（はっぴょう）に先立（さきだ）つ準備（じゅんび）に時間（じかん）がかかりました。
The preparation preceding the presentation took time. (先立つ before a noun)
Breakdown
新学期（しんがっき）に先立（さきだ）って、教室（きょうしつ）をきれいに掃除（そうじ）した。
Ahead of the new term, we cleaned the classroom thoroughly.
Breakdown
⚠️ Often confused with
〜た後で / 〜後
After doing 〜後で
"After doing ~". Attach to the ta-form of a verb, or a noun + の. Note the contrast with...
〜てから
After doing (and then) 〜てから
"After doing ~ (and only then ~)". Emphasizes that action B happens AFTER action A is comp...
〜前に
Before doing 〜前に
"Before doing ~". Attach to the dictionary form of a verb or a noun + の. The action AFTER...
〜たとたん（に）
The moment 〜たとたん
"The moment ~", "just as ~" — the second event follows instantly and unexpectedly.
〜次第
As soon as 〜次第
"As soon as ~", "the moment ~ is done". Formal, and always about the future.
〜以来
Ever since 〜以来
"Ever since ~" — a state that has held continuously from a past point until now.
〜たびに
Every time 〜たびに
"Every time ~", "whenever ~" — the second thing happens on each occasion of the first.
〜ぶり
After an interval 〜ぶり
"After an interval of ~" — how long it has been since this last happened.
〜かと思うと
No sooner than 〜かと思うと
"No sooner had ~ than ~", "just when you think ~" — two events tread on each other.
〜上で
After (formal) 〜上で
"After ~ing (and on that basis)" — a deliberate step taken before deciding.
〜ところに / 〜ところへ
Just as / right when 〜ところに
"Just as ~", "right when ~" — something arrives at exactly that moment.
〜際（に）
On the occasion of 〜際（に）
A formal "when ~", "on the occasion of ~".
〜てはじめて
Only after 〜てはじめて
"Only after ~", "not until ~ did I …".
〜てからというもの
Ever since then 〜てからというもの
"Ever since ~" — a turning point after which things have stayed changed.
〜に際して
At the time of 〜に際して
Formal "on the occasion of ~", "at the time of ~" — used as something significant begins.
〜が早いか
The instant that 〜が早いか
"The instant ~ happened, ...", "no sooner ~ than ...".
〜や否や
Scarcely when 〜や否や
"As soon as ~", "scarcely had ~ when ..." — the two events are almost simultaneous.
〜そばから
No sooner done than undone 〜そばから
"No sooner is ~ done than (it is undone)" — the effort is immediately cancelled out.
〜なり
Immediately upon 〜なり
"The moment ~", "immediately upon ~ing" — one action leads straight into an unexpected nex...
〜を境に
Marking the turning point 〜を境に
"With ~ as the dividing line", "ever since ~" — a clear before and after.
〜がてら
While also doing 〜がてら
"While ~ing", "taking the opportunity of ~ing to also ..." — two purposes in one outing.
〜間際に
On the verge of 〜間際に
"Just as ~ is about to happen", "at the very last moment before ~".