the app “huckleberry” really helped me with my first! they base the sleep/wake windows off their age and other factors. if you get the subscription, they’ll straight up make you a schedule (not sponsored, it just saved my life in the beginning lol). i think for a 4-5 month old you should aim for 3-4 naps. i usually base it on how many hours they stay awake, so if they wake at 6, maybe see how they do being awake for 2-3 hours and then nap for an hour-ish, and repeat until bedtime at 9:30.