Is there any definite period for the usage of the idiom "long gone" in a sentence: could it be used if the time has only passed a year?

Much less than a year :-)

Long Gone Before Daylight - it's clear to any competent English speaker what has happened here.

Is there any definite period for the usage of the idiom "long gone" in a sentence: could it be used if the time has only passed a year?

Much less than a year :-)

Long Gone Before Daylight - it's clear to any competent English speaker what has happened there.