Hello Devonshire

Welcome to PCHF
There is really nothing you can do about something like that. If you are going to continue using the old monitor, just turn it on a few seconds before you turn your computer on if you need to see the splash screen.
There isn't a setting that changes the warm-up time of a monitor. None that I know of anyways.
I don't know if that answers your question or not, but I hope it helps!
