Both my boys were pretty young when I first left them, but it wasn't for long, say 30min to an hour. Si's first time I think he might have been 2-3 weeks old, and mum was over, I fed bub and then dh and I nicked out for coffee.

Some lessons from that - you have to want to do it, and bub should be left with someone you trust!
If you don't want to do it, and you don't trust the person - it's a no-brainer Leash.