It’s a best practice to use VPN when you connect to public Wi-Fi networks. However, in the scenarios I am aware of, you first connect to the network and only then—after connected—switch to VPN. In that case there is time-window when your traffic goes on an insecure connection and you are vulnerable.
My concern is many programs/services/processes running on a PC execute a housekeeping/update check/status check as soon as a network connection is available. And all those activities would be performed via an insecure connection if they are triggered before the switch to the VPN connection.
Is it possible to avoid this?