When is my son old enough to stay overnight with me?

My son will be 3 months (13 weeks) old this Friday. Unfortunately, his mother and I aren't together, but I love him to pieces. I work away from home for 2 weeks and then I'm back for 1 week. I try to visit and spend as much time with him as possible, but never as much as I would like because his mother only wants me around for so long. Whenever I ask about overnight stays she simply says something along the lines of, "yeah, when he's older". How old is old enough to have overnight stays with me? I want to do as much bonding as possible, but it's difficult when I only see him a few times ever 2 or 3 weeks. I'm trying to be more informed about visitations and such. via /r/Parenting http://ift.tt/2e3eb5P