Good! You were supposed to, because that's when "not normal" starts.

To establish your normal, you could start your story while she's in the process of carrying out a hit, getting hired, getting paid, going over her calendar of this month's jobs, or whatever, to show she does this a lot. This is every day life, and it's interesting. Then she gets The Big Job Offer, and that's her inciting incident, her call to adventure. When she accepts the offer, she crosses the threshold and embarks on the journey that will presumably change her. In the end, she won't be the same hitwoman she was before she took this job. Your job this month is to figure out how and why she'll change.

Cheers,
Michelle