You'll be fine. To be honest most VPN marketing is just fear-mongering. Most things you do are encrypted anyways so public WiFi isn't that risky.
If you are concerned these things will be much more helpful than worrying about this small race:
Use some form of encrypted DNS like DoH or DoT.
Enable the "Always use HTTPS" setting in your browser. This way you won't make an unencrypted connection without manually approving it first.
Turning the VPN before connecting to WiFi may help but it depends how it is implemented. The VPN connection will need to be re-established on WiFi. So unless your OS blocks network traffic until that happens you may still leak. IDK if any phones have strong settings here.
Thanks. But hypothetically even in that scenario if I'm offline and I want to turn VPN on, first I need toconnect to internet and then trought that initial connection communicate with the vpn server to turn VPan on. Right? So I'll still be volnurable for a moment especially if a lot of app are programmed to sent data onlne the moment they find internet access.