Baemon did a lot of rehearsals for the pre-recording, might be more than 10 times if OP includes the rehearsals for Monsters (Intro), too. Another fan said Ahyeon was in the center for Monsters.
#BABYMONSTER#베이비몬스터
10.5. Outfit summary:
Asa Pigtails + Choker + Arm Long Sleeves
Ruka Straight Hair + Black & Blue stockings
Ahyeon Half-Up Hair + Big Ribbon
Rora Half-Up Hair