If it's an infant then I wouldn't want the baby away from momma at all until at least 6 months & then after that for short times & not overnight until after a year (and for me I wouldn't agree to it until weaned & in my state as long as dad has good access, they will delay overnights with a nursing child until age 3). That is just my personal opinion based on what I know of human attachment & the security babies feel when with mom - especially nursing babies - because they do
know momma is the source of food.
Ideally you do what is best for the child
& I do not think overnights away from mom are good
for infants, at all, no matter who they are with.
This explains it better than I could ever... http://www.drmomma.org/2010/07/mother-toddler-separation.html