Get your instrument, commercial, multi, CFI, CFII then instruct on your off days over the next 9 years. Build time and network. You might get a Part 91 or 135 break by knowing people at your local airport and get yourself into a King Air or similar on off days. If you want an airline opportunity by the time you retire, it will be there for you. Under no circumstances do NOT quit your current job till you retire. You will still have 22 years of Part 121 eligibility.