As a fan of the genre, I really hope you don't implement the cross-progress locking mechanic that was suggested recently. Games like "Harem of Sultan" tried this, and it completely ruins the pacing, turning a fun visual novel into a frustrating math spreadsheet.
From a worldbuilding and biological standpoint, locking progress makes no sense here. These office girls have completely different personalities and metabolisms. Forcing an endomorph character (who naturally gains fast and loves food) to freeze her progress just because an ectomorph character isn't at the same stage completely destroys their individuality and breaks immersion. Please let each girl progress organically based on our individual choices with them, rather than forcing artificial roadblocks!