expression
on the occasion of; at the time of; when doing
Formal expression used before a noun or verb to mark a special occasion or the start of an action. Often used in speeches, announcements, and formal writing. The related form に当たり is more formal and often used in written language.
See also: に当たり
開会に当たって、一言ご挨拶を申し上げます。
On the occasion of the opening, I would like to say a few words of greeting.
新しい事業を始めるに当たって、しっかりとした計画が必要だ。
When starting a new business, a solid plan is necessary.