How to change the order of startup applications?

These will start in alphabetical order, so you can name the startup application 0-Chrome to start it before the others.

You can use a startup script and make it look like:

#!/bin/bash
app1 &
app2 &
sleep 2s
app3 &

Make it executable and add an entry in the startup applications like:

sh /path/to/startupscript.sh