Malcolm,

You could also do this via a Timer Interrupt using DT's Instant Interrupts.
Say, Timer2 (8bit timer) with both a Prescaler and Postscaler, then in the ISR decrement a word variable that is preset to a number that gets you to 3 seconds or whatever time you want. When the var reaches zero set a flag to run the display routine and reset the word var back to your preload value. In your main loop test for the flag and call the display routine if set and then clear the flag.

This would allow you to hit a time-based delay much easier.