late Old English timlic "quickly, soon;" see time (n.) + -ly (2). As an adjective meaning "occurring at a suitable time" it is attested from c. 1200.
a timely warning
with timely treatment the patient has a good chance of recovery
the timely filing of his income tax return
time zone
time-honored
time-keeper
timeless
time-line
timely
timeous
time-out
timepiece
timer
time-server