Punctually or according to the schedule. / By installments, payments over a period of time. / (chess) By a player's running out of time.

Punctual or according to schedule.

Alternative form of on time.

Alternative form of on time.

from time to time

On or near the same date (in the past or in the future). / On this occasion (as opposed to last time or next time).

plural of timing

Never.

It was once true (that)...; there was a time when...

When (some future event has come to pass).