Concerned about who's going to watch my son after maternity leave is over. Any advice?

I'm just 5 months pregnant with my first child. I'm due Feb 18th and planning to work up until the week before my due date if that's realistic. I heard women being able to do that. I heard maternity at my job is 12 weeks with pay. Now after 3 months unless I decide not to go back to work for awhile I'm worried who's going to watch my son. My husband and I originally planned to have his mother to come on a visitor's visa from Nigeria but we don't know if this is going to work and he doesn't have any other relatives here in the US. I'm not sure if I can find relatives on my side of the family willing to babysit.