re: 5 months away from graduating w/ an MA - When should I start applying for jobs?

Start yesterday. Is your search geographically limited? If so, get off campus and start networking. Hit up every one of your profs and tell them you're job searching and ask for referrals. You never know who has a consulting client, spouse, etc in need of a technical writer, trainer, or other position relevant to your skill set. Can you get an adjunct gig teaching at night? That sort of teaching works alongside most any day job, and it's easy money.