Exact timing: とたん, 次第, たびに, 最中, 以来

These patterns pin down when, more precisely than とき or あとで. Each takes a plain-form verb (or noun) and attaches a time word.

Past plain form + とたん(に) = "the very moment that". The second event is surprising or sudden.

Because it is a surprising fact, the second half cannot be an intention or request.

Polite stem + 次第 = "as soon as". Formal; often used for promises and plans.

Unlike とたん, 次第 looks forward: the second half is the speaker's action.

Dictionary form + たびに (or Noun + の + たびに) = "every time".

Number + ごとに or Noun + ごとに = "every..., at each...":

Verb + ている + 最中(に) or Noun + の + 最中に emphasises that something is in full swing, usually when an interruption occurs.

Noun + の + 途中で or Verb + 途中で = "on the way to / in the middle of".

て-form + 以来 = "ever since...". It states a continuous state beginning at that time.

• 食べる前に (before eating): dictionary form + 前に
• 食べた後で (after eating): past form + 後で
• 食べてから (after eating): て-form + から
• 食べる最中に (in the middle of eating)

Negative form + うちに means "before it becomes the case that":

Timing patterns often appear in procedures, rules and stories of habit.

• たとたん: the instant that (surprising). 次第: as soon as (forward-looking).
• たびに: every time. ごとに: at every.
• 最中: in the middle of. 途中: on the way. 以来: ever since.
• ないうちに: before it changes.