Have any of you done this yet? Do you think it makes a difference if baby is formula or breastfed? When do you feel like you'll be able to do this if you haven't already.
I have a cousin with a not quite 3 month old who leaves her son overnight with his grandmother several nights a week so that she can babysit when my cousin is at work during the day. I just can't imagine doing this, even though I'm sure she wouldn't if she had any alternative. I still haven't left Ellie overnight and we still co-sleep so even if she eats in the night, I'm not really awake for it.

I do think that we're probably going to leave her overnight with DH's parents when the last Harry Potter movie comes out because I'd like to go to the midnight showing opening night.