tummy time?

mpstochlinski8

how often and how long do you do "tummy time" with LO? our twins will be 1 month tomorrow, we just started doing it last night with them since their navels are now healed. have an appt with their pedi tomorrow, will ask him but wanted to hear from other moms what you do for it? do you position their arms for them or just let them do their thing? TIA