In the dim and distant days of full time weather observing, we used to
record the time of onset and cessation of precipitation from a visual
observation. As has been said, it could be well over an hour before the
tipping bucket registered, and maybe 4 or 5 hours with a fine drizzle.
In fact during lengthy spells of coastal drizzle my personal definition
of when it had changed from light to moderate, was prompted by the
tipping bucket measuring 0.2mm. It is not unusual for there to be many
hours of drizzle but to only register a 'trace'.