With DD1, born at 4:36pm, my dad and Aunty had just been to visit me while I was labouring, went for a coffee and came back to knews that DD1 had arrived so they knew straight away. DH called his parents and sister straight away pretty much and I messaged everyone else and I added in the message what time visiting hours started in the morning so they knew they could come then. So we had my dad, Aunty, PIL, SIL, and one of my closest friends come straight away but I was happy with that. My mum lives 10 hours away so we rang her on the way to labour knowing it would be another day before she arrived.
DD2, born at 2.30am we did not tell anyone until early morning, around 7am I think. Both very different but I enjoyed both ways very much.