For Sustanon there is no such fixed time period. I estimate that after the last injection levels drop to one-half by the 4 day point; to one-quarter by the 10 day point; to one-eighth by the 16 day point; and to one-sixteenth by the 23 day point. Or if preferring to work with round numbers in terms of percent, as approximate values levels drop to 40% by day 6; to 30% by day 8; to 20% by day 11; and to 10% by day 18.