Eldest DD was sleeping at friends from about 2-3, DS slept over at grandparents from about 10 months (sheer neccessity), DD2 goes to my mums occasionally.

I remember thinkning it was weird when one of DD friends parents called concerned her daughter would not cope with a sleepover at the age of 10! I didn't realise, it is such a normal thing to sleepover at our place.