You just have to account with the two advancing your frame. So you would Vs. Seek the two that can be rechallenged, save in the grass. Hit your time and delay and SS immediately. Check what frame this pokemon is on(determine its IV's and Nature and scroll through the main window of the RNG reporter) it should tell you "about" how much you have to adjust.
So if your frame is 21, and the frame you land on is 18(including the SS) then you have to find a way of doing 3 advancements.
Thank you! But to check my delay, don't I need to do the coin flip, which would make the NPCs advance the frame a ton? Also, to do the "3 advancements" or whatever, I would just do that amount of turns in the grass, correct?