Toddler Napping in New Surrounding

I have been a SAHM since my son was born and am starting a nannying position next week where I can bring him with me. I'm worried he will have issues sleeping since I usually rock him to sleep if we are somewhere unfamiliar. With two other children to care for it will not be able to sit with him to do this. They are providing a pack and play for him to sleep in but I need advice for helping him fall asleep if I can't physically stay with him to comfort him.