See what happens. If they don't, get them up and try it again later that day or the next night. You're suggesting that this takes a bit of time and patience. Well, you never know. You know parents are often shocked.
Some babies just go right to sleep and the parents are stunned.
But the more you do it, and the more often you do it, the more this is going to seem comfortable to the baby. After a point, typically parents really see a pattern emerging. Some babies are taking two naps a day, some babies are still taking three naps a day, and that's fine. But you start to see a pattern emerging for most babies by around eight weeks. So, once your baby's up for two hours, that's the time to put them back down for a nap.