Ya, 30 seconds is an awfully long time.

You could always use something like xwininfo to verify it's running.

For example, if this fails, you have no server running -

xwininfo -display :0 -root

Return on fail should be - "xwininfo: error: unable to open display ":0""
I think xset q could be used, too.

xset -display :0 q

I wouldn't fiddle with gdm - I only use a basic wm and want the minimal work requests to the video card.