Delaying starting while ECU boots up is a good idea. It allows the program to go through its checks etc and initialise fully.
I tend to do that (but not always) in any car with ecu. My thoughts are that no external signals will come from the engine sensors during boot up and possibly cause a glitch when picked up.
Maybe not critical in a newer car but an older one may not have the software to cope with it.
Worth trying anyway.
