Is there a way to automatically request fuel and catering as I start my preflight procedure and start boarding, let say 30 minutes later ?
I'm not sure I understand your question: what's stops you to call catering/fuel, do the preflight procedures, and start boarding when the times comes ? Do you mean you wanted to do it *unattended*, when you are away from the keyboard ?
Not possible with GSX.
But maybe you can use some kind of software to send keystrokes, which might offer a feature to send timed keystrokes, so you could send CTRL+Shift+F12, then the 4 (I think Boarding it's the 4th menu entry), on a specific time.
