This app was mentioned in 14 comments, with an average of 4.14 upvotes
So Depending on their age I would download the Switch Parent App
You can control what they play and also see how long they are playing.
Second you'll need to create a nintendo ID. That doesn't take long a few minutes. Then after that connect it to wifi to download updates and everything (depending on the game this could be 10 minutes - 1 hour plus+). After that you are done. You will have to open the games and put them in the console to get the updates.
The dock is super easy to set up just a Power Cord and an HDMI.
So if I were you I would open it up set it up and wrap it back up. Unless you want your kids to experience opening the full thing and setup.
Try signing in to the Parental Controls app (App Store, Google Play) and seeing seeing if your console is registered with it. If it is, try to unlink it from there.
It seems this is going to be Android's link.
However it doesn't work yet (at least for me)
https://play.google.com/store/apps/details?id=com.nintendo.znma
You can track time with that.
You need to download the Nintendo Switch Parental Guide app.
https://play.google.com/store/apps/details?id=com.nintendo.znma&hl=en
This worked for me. https://play.google.com/store/apps/details?id=com.nintendo.znma
Also Android
Youll need to set the system up, it will walk you through the start up process. You can just plug the ac adapter into the bottom of the system and set it up with out a TV to do it discretely.
First and foremost, youll need a nintendo account. You can put in an email address during the start up and it will send you a link. Or you can make one here: https://accounts.nintendo.com/
Once all setup and connected to the internet it should ask you to download some firmware updates, those shouldnt take more than a few minutes. If it doesnt prompt you to do so, tap the Gear icon on the bottom of the home menu to visit the system settings at the very bottom is a system update button.
Then you can visit the eShop. Which is the little shopping bag on the bottom of the main menu. On the left hand side is a "redeem code" option, put in the code and the game will be added to your account.
Note: games are tied to the account used to redeem or purchase it with. If you want your kids to be in control of the games in the future, maybe register the account under an email address made for them. There is a Parental control app for iOS and android you could use to keep watch over it in the mean time.
Free to play games like Fortnite, Warframe, Arena of Valor, and Paladins, do not require the subscription to play online. But Mario Kart does.
This is what I see when I open up the app. This is the specific app - Play Store
https://play.google.com/store/apps/details?id=com.nintendo.znma
It has more detailed statistics.