How to set a reminder when the computer is turned on?

I'm not sure what you're talking about, but I mean to send a message to your mobile phone as soon as the computer is turned on. If so, it should still be possible. The software used is WeChat or qq, because both of them have pc version and mobile version, and people use them more. You can install one of these two softwares on your computer, set it to log in automatically, and your mobile phone is also installed. As soon as the computer is turned on and logged in, the phone will remind you.