Postpartum Depression Plan

I am 20 weeks pregnant with my first, i have a number of the risk factors for PPD,

I realize that this condition is still quite rare among new moms, but I can’t ignore that I am uniquely prone.

I am afraid that myself and my support system will not be able to distinguish between regular baby blues and full on depression. Is there some kind of plan I can put in place? Something to tell my husband to look for? Should I schedule appointments with my therapist after a certain amount of time? Are there specific thoughts I should see as red flags?