Steam is easy, just don't open it!
Windows has a setting somewhere that lets you manually start the update, unless it is mandatory for security.
For me Nvidia drivers only update when I say so.
Same here. I only download updates by choice. There is an old IT saying, "don't download updates on release". When it comes to any updates, the potential for breaking EVERYTHING is high. I always give it a day or two for the repair patch to make it's way down the pipe. Updates are like a bull in a china shop. They can occasionally, unintentionally ruin everything. Give them a day to realize what they fucked up before applying them.
For steam, just go into your library. Left click on all your installed games, click on properties, and in the window pick the tab "updates". There should be a drop down menu that allows you to choose when you want to allow your games to be updated.
For Windows 10, I would highly suggest going through your update preferences and picking what you want. Click on the windows icon in the lower left, then the gear for settings, then "advanced options" to pick how you want the updates to download and apply. Also, if you haven't been there yet, go to settings/privacy. The liberties that Windows 10 takes with your personal information is staggering. If you haven't gone through the privacy settings yet, they have access to pretty much everything you go to, everything you type, everyone you talk to, everyone you connect with, and pretty much everything you do. I really wish there was a tinfoil hat involved with this one...
For Nvidia, it's all about removing the "GeForce Experience". Once that is gone, the autoupdates should stop. You will still get notifications that an update is available, but it won't be forced down your throat like a bad porno...
All that said, updates are EXTREMELY important. If you abandon the auto updates, you will definitely need to manage those updates yourself. I have had to do a complete wipe and reinstall of my main drive because i neglected my updates for too long.