My lo stayed over at my mum's on Monday, it was my birthday, so we wanted a few drinks and haven't been drunk together for so long and very much needed! Lo is almost 16 weeks, and at the moment doesn't get seperation anxiety, so I feel it was perfect timing.
Obviously it is so up to you though, if you are not happy leaving your little one, then DON'T do it, you will have a poor night and isn't worth the stress.... I left lo for the first time when he was 10 days, it was with his daddy, whom I trust with my life, I'm personally so glad that I did it then cos I think it does get harder. My partner and I started to have lunch dates, cinema and food during the day and James has been going to my mum's about every 2 weeks for an afternoon. My friend has a 9week old and she has NEVER left her lo, she keeps making plans with people, but cancelling cos she just doesn't want to leave her.
I would never let my lo stay at my in-laws, they can come to our house after a phone call, (MAD) granny rights and all. I don't like them, but that is a whole other story.....
Good luck with the upcoming event! You will be surprised at how much you can love something and how the loves grows every day!
x