Crikey! I waited a whole 3 hours before trying out my new machine. 9nly left it that long because it arrived on new year's eve and was very cold from its journey. (I was also surprised that it had arrived already, since I only ordered it the afternoon before!)
I did wait a day before trying out my overlocker but that was because I'd never used one before and was terrified of it, so wanted to be sure of having a clear hour or so to get to grips with threading it and trying different stitches - and the different coloured threads I'd ordered so I could see what was happening hadn't arrived yet!