I just got the CJO in March. I had a total of three internals, with two being just standard airlineapps recs by Delta pilots and the third being the HR email to have my app scored.

I also attended two job fairs. It was about one to two months from the internal HR email until the invite (assuming that is, in fact, what pushed me over the edge to get the interview).

One other thing, I made sure to go through my app line-by-line (and I had my wife go through it as well) before having my friend at Delta send the email to HR. I thought I had it pretty squared away but still found some minor mistakes. I didn't get a "fix-it" email, just the invite. I think it's definitely worthwhile to check it thoroughly and hopefully skip the "fix-it" email.

Good luck and I hope that helps.