But before just running sheiko straight after 531 (once a week squatting), id be working my up to sheiko level volume and frequency. Dont just jump in. (Though just jumping in will work...if you survive).
Personally I add a second squat day to start with. Then a third. Then move into sheiko.
This could done over 4 weeks.
2 weeks of 2 a week, 2 weeks of 3 a week. Similar approach to a smolov prep phase (or whatever they call it before heading to normal smolov).