I have 3 on my own.
I do whatever is easiest. Often I am flustered as I cannot wait until they are all asleep.
My big girl is reasonably easy. She just goes to bed. Often with a short DVD, audio book or a book, but she knows when she is tired and just goes to sleep. She also has a room away from the other two.
DS has recently become a nightmare. And often I have to resort to the outside threat too. We have a read/ milk. He used to just roll over and go to sleep. Lately he is awake for hours, so often he has fireman sam on repeat on the DVD player. He cannot just roll over and go to sleep. Often he is hungry (because he doesn't eat during the day ). Sometimes if I sit with him he will go to sleep, often it's a long and protracted battle.
The littlest Miss, she goes when she's tired. If that's before the big kids, ace. Otherwise she just potters around until it's her turn or she's too tired. She's a feed to sleep kid though, so often I do it while I sit with DS.
I start the process early with dinner and baths.