This summer in Mykonos our flight back to FCO was delayed and nobody at the airport could communicate reliable estimates on when it would be.
In that case I managed to find the FCO-JMK inbound flight on FR24 and saw it left FCO with 2 hours delay, so our own would have been at least that.
In bigger airports with more connections you might not be able to guess which airplane will become yours.
I guess the registration number of the plane assigned to my flight will be available some time (maybe a few hours?) before as per the flight plan.
Is there a reliable public accessible source for that?
When I have the assigned RegNum I can use plane finder, FR24 or whatever to see if it's on its way and have a rough estimate of when it will land and then be available for my flight.
Apologies for my English.