Well if it's a Lilliput, you could use the Coyote Auto-Power-On mod... I do.. works great.
If it isn't, then yea you'll need a nice 555 IC circuit... and make sure you use a relay
to trigger the "button" of the screen so you don't accidentally send +12volts thru it!
Lemme look around and find a good 555 circuit and post it.. or anyone else that beats me to it
How long of delay do you think you need?