You are off to a good start, but I think being tied up another 3-4 years to try and get on with JB might be "time a'wastin". Many regionals/commuters are hiring pilots with 650 hours or so. You can get that pretty easy by instructing. Since seniority is EVERYTHING in an airline job, you can't let too much time go under the bridge or you'll be on the backside of the powercurve. Continue what you're doing, and try and fly as much as you can on the side. Try and network a bit while you're building your hours. A friend of mine once said "if you know FIVE people, you can meet just about anyone you want". I've found that to be fairly true. A lot of the time in this business it's WHO you know. Good luck to you.