sudo chmod 755 /path/to/sh.script
throw it into startup applications.
#!/bin/bash
dbus-send --system --type=method_call --dest=org.freedesktop.NetworkManager /org/freedesktop/NetworkManager org.freedesktop.DBus.Properties.Set string:org.freedesktop.NetworkManager string:WirelessEnabled variant:boolean:false
Note: This only applies to having your wireless card attached during startup.