Seeking advice for very early career switch into finance

I graduated this past May with a degree in economics from a non-target school with a 3.6 GPA. After graduating I impulsively took an economic analyst job doing housing/installation consulting for the US Military and have really come to dislike it (industry is boring, pay is in the 50s with no bonus, not a lot of opportunity for development, no formal training, etc.). I always had the intention of working in finance--I've had internships on a corporate development team and at a boutique M&A advisory firm and really enjoyed them--and would really like to make a switch. How should I go about this given that I missed recruiting in September? What kind of things should I be doing to maximize my chances of getting my foot in the door at a respectable firm?

Thanks in advance.