>>41528925You don’t. You basically set your text speed to slow, use the link at the end to find where you need to go and save. Then toss in a Wishing Piece and press home like a half second later once the “Saving your game” text rolls up (the Saving doesn’t start until the text has fully rolled in, thus the slow text speed). However, it does roll for RNG to determine if the WP gave you a common or rare encounter as soon as the text loads, so you have a second or two to see if it’s Red or Purple.
If you got Purple (or red, if you want common) then switch your text back to fast and save. Then start the encounter and if it’s the Pokémon you want, grab it. If it isn’t, first press Invite a Friend and then press Home, go to System Settings, System, Date and Time and roll it one day forward.
Because you were looking for other players and that a day has elapsed, the game thinks “oh shit I’m sorry” and resets the spawn at the Raid.
https://www.serebii.net/swordshield/maxraidbattledens.shtml 
