If the official tools aren't working, you can check when your Google account was first linked to the device. Go to > Google > Manage your Google Account . Tap the Security tab and scroll down to Your devices . Select Manage all devices and tap on your Xiaomi phone.
While "Up time" only shows how long the phone has been on since the last reboot, some regional ROMs include a "First power-on time" field in this deep menu. Method 3: Using Third-Party IMEI Checkers how to check activation date of xiaomi phone
By learning how to check the activation date on your Xiaomi phone, you can: If the official tools aren't working, you can