How could my privacy be compromized in the time between me connecting to a public/work wifi hotspot and the time my vpn is connected.
Is there any use in 1. turning on my mobile data, 2. Connect to vpn, 3. Switch to wifi? Or it is just unnecessary and convoluted.
To avoid this leak, you should use a firewall rule to forbid the outbound internet traffic to anything except the VPN IP address.
There is a good post about doing this using UFW on Linux: https://www.linode.com/docs/guides/vpn-firewall-killswitch-for-linux-and-macos-clients/#vpn-firewall-using-ufw