When I first got my instructor (AFI) rating, I was in a similar position to you. I had a decent job working shifts, with quite good salary and benefits, which I didn't dislike too much.
It was the thick end of twenty years ago, but I chose then, not to give up the lifestyle I had to go instructing FT. My shifts were 12 hours, 4 on - 4 off, so about the same time off as you, but predictable months in advance, which may have helped.
What I did initially, to get my first job, was agree to teach groundschool for the MoD FSS. They were getting 30 hours each at the time, but you couldn't do it unless you had at least 100 hours instructional. Of course, once I was working for the club, I started getting TLs and checkouts to do and once the first course was finished, the ones that opted to pay to complete their PPLs needed an instructor, so I got quite a few of those to do as well. The important thing is getting yourself a start somewhere, whatever the job, be it op's, groundschool or whatever, once you're there the flying will start to happen.