DL's old rule was that it would be the first Saturday after the qualifying event. That's when they'd "run the tapes." (I imagined a huge reel-to-reel machine in the basement of the ATL airport :-). This is exactly what happened with me last year on DL when I hit SM, then GM, then PM...It always happened in the wee hours of Saturday AM, Eastern time. Earlier this year, I heard they started "running the tapes" less often, perhaps every 2 weeks or month (a month is crazy!).

But the consolidated SM program is running off of NW's system. In NW's system, the new status took effect the day after the qualifying event. So that might be the case now.

In any event, reservations booked before or straddling the qualifying event might have problems. Most likely they'll fix these for you after the fact. I would suggest that for any future reservations made before the qualifying event that you go online, delete the SM number, then reinsert it. This always worked on NW in the past.