Originally Posted by ethernal

I'm assuming that it is a split ticket itinerary so unless they make an exception they may not let you into the lounge until T-3 hours as Delta won't consider that a connection. My understanding is that the Delta One lounge access rules are "in addition to" the standard Skyclub access rules (so the 3 hour rule applies even though the Delta One lounge rules just say same day Delta One ticket).

I don't have personal experience here (only time I've been in a D1 lounge more than 3 hours before departure was on a connection) but at least be psychologically prepared to be turned away unless you've confirmed they'll admit you 6 hours early. I could be wrong.