First off, find you some alone time, far away from the children. I know, impossible right? Just throw one piece of candy in the middle of the floor between the three of them and walk away. Boom, you just bought yourself 30 minutes. You can now leave the room knowing that your kids will be occupied and probably only one or two of them will get hurt. See, I told you, I know my shit.
Now that you have some alone time, it's time to start practicing. First, stomp around for a little bit. Don't make your footfalls to hard. Make them hard enough that they can shake pictures off the wall but not plaster. Find your sweet spot and practice that. This will be important to master because how else are your kids of all ages going to know that you are about to lose your shit if they don't get to bed? Stay with me, it gets better.
While you are stomping around start working on your "I'm getting frustrated" face. This is a face that you make somewhere past "Jesus H. Christ" and right before "You're not mine." Once you got that face just right, practice alternating that face in between your stomping. Remember, a successful routine is all about presentation. The key is to instill the fear of god on them without giving them nightmares.
Ok, now for the next step. Spend the next 5 years establishing a bedtime routine for the older two and then have a third kid to fuck it all up. Remember, this is a marathon, not a sprint. Just have yourself some tired sex and pop that third kid right out. It's easy, people do it all the time. It will be great. Because without the third kid, how are the other two supposed to forget how to go to bed?
Once your third kid is about 3 years old and can understand words like "right fucking now", then all your prep work is done and it's time to start establishing your bedtime routine. You are going to use all that practice to great effect pretty soon, let's get to it.
Your first step is getting them ready for bed. So line them up and tell them all the brush their teeth. Wait 30 minutes after you have told them and then tell them again. It's all about repetition at this point. After another 30 minutes ask them if they've done it, have them lie to you, call them on their bullshit and then sit on the toilet while you watch them brush their teeth for the theoretically third time that night. You'll have to help the toddler though but just throw water in his face until he at least smells cleaner.
After that, tell everyone to go get there pajamas on. Remember to be clear with your instructions though. Don't say "go get ready for bed." That is going to screw you every time. Say "go get your pajamas on, don't try to sneak downstairs and watch minecraft videos, don't go outside, don't try to feed the pet ants that we suddenly have and don't go into each others rooms which is beyond me why you would do this anyway when you are supposed to go get ready for bed. Seriously, we have been doing this every night for your entire lives how can this be so hard?"
While the older kids don't get their pjs on, spend some time with your youngest child getting his pjs on. This will look like a WWE wrestling match except it's 100% real and when he headbuts you in the nose, and he will, you really will bleed.
Good job parents, you are halfway there.
Next, your oldest child will come to you explaining that she hasn't done her homework yet and this will confuse you because you asked her right when she got home from school if she had any homework and she said no. Now she will tell you that she forgot. But that's ok, it's only a small project where she has to do some drawing. She will ask if we have poster board, glue, glitter, pipe cleaners, a 1972 quarter and anything that could resemble planet earth hung from a coat hanger. Give her a twist tie and a brown paper bag and tell her to make due.
Now go find your son. He's probably wondering around the basement somewhere looking for Pokemon. Remind him to get his GOD DAMN PAJAMAS ON JESUS CHRIST.
Now off to handle the toddler. He will be playing in mom's makeup. It's a given, it's going to happen. Throw that little guy over your shoulder and wrestle him into bed. Have him pick out his favorite 2 books that he gets for bed time stories. Be prepared to read these 40 or so times but only make it every other page before you are interrupted by one of your other two children. Punish them by forcing them re-enact scenes from your favorite Western thus insuring that the interruptions will soon end.
After you have read your 40 books calmly explain to your toddler that you just can't freaking take it anymore and that they need to go to sleep and suck it up. Then find your other two children who have by now changed out of their pjs and are instead wondering if the dog will eat pencils. They discover that he will.
Now is the time to use your frustrated face and your stomping. This is why you practiced all those years ago, time to put it into action. Stomp, scowl, stomp, scowl, stomp, scowl, eventually they get the idea that you are about to lose it and god help whoever is near you when you do. Tell them it's lights out but then have them promptly ignore that while you yet again put the toddler back to bed because he's gotten out of bed and he thinks that's funny.
Finally, shut all bedroom doors with warnings that if anyone comes out of their rooms tonight they are gong to mow the yard in the moonlight and no, you are not kidding, not one bit.
Great job, you have completed your bedtime routine! For a celebration, head to your strategically placed lawn chair that is at the corner of the hallway and play on your phone. This is your little reward, go you! When you here a door open just say "BED!" and don't even look up. Eventually you will get to go downstairs and delete that football game you recorded because it is now midnight and you are never going to watch it anyway.