If you started your training today, you could expect 12 months to CPL/instructor rating or Instrument rating. Expect to spend possibly another 4-5 years in GA doing it the traditional way before possibly getting in a regional turboprop, who knows how long there until a jet.
Another option is a cadetship with a regional?
As already mentioned here GA has changed a lot from what it was. But that doesn't mean you can't do it, just don't expect to be earning $100k for a while.
Having said that, I left a well paying career and started flying a bit later than most of the young blokes coming through, I accepted the risk and the lack of financial income for doing something I loved. Looking back, Im bloody glad I did make the change. You gotta be happy doing what you do.