General timeline for paper work etc..

One thing I have been stressing out about besides hoping my baby is doing everything it's supposed to in there, is paper work... I am 19 weeks, have my anatomy scan on Thursday, but what now? My SO just started a new job after being off for about a month so his income will be helping soon, though I make more and am in charge of our finances. I plan to leave my job either directly after maternity leave, or not too long after due to where I am work. Sooooo I guess I'm wondering generally when I should talk to HR more about leave and payment, and since I will be losing my insurance when I leave, could I go ahead and apply for Medicaid now? And any other things I need to do... I'm lost.

-STRESSED FTM