A common and wise response to these questions is always abide by the aircraft's POH/Manual. So, I've looked at a number of these today. I have yet to come across a POH that mentions "downwind" in any section. The terms used are variously; 'Pre-landing', 'before landing' and with one referring only to 'final' and 'short final' (neither of these terms are defined as a distance from landing).