Our daycare (up to age 18 months when they put all babies to one nap) will follow whatever routine you give them, so the generally are not putting all the babies down at once. Not sure where you are in the world, but here the ratios of carers to babies is high and daycares have limits as to how many infants they can have at once (ours can have 6 under age 18 months I think). Plus children really are very adaptable and will catch on quickly that how the nap at daycare will be different.