15 -20 years for an A320 Left seat is about right at the moment. 20-25 years for a widebody. This has all been done before in another thread, but for the newbies, go in with your eyes open! A great job in some respects, and a terrible one in others. Assuming these 787's stop spontaneously combusting and actually turn up next year, and retirements kick off then it could be a good time to get in. Rumour has it that 400 pilots hit 65 in the next ten years. Despite the odd one hanging on into their dotage, the average retirement age is still 65 so barring another SARS/9-11/swine flu etc, things should start to speed up.
That said, make sure you apply for the right reasons. If you want a quick command (or even FO) then go to Jetstar.