Posting System?

Yes. As I understand it, the club can do so whenever it wishes. However, the teams want to have the talent to put on the field, so they tend to wait until very near the limit.

Possible? Yes. Probable? No.

Japanese teams have players basically trapped for a minimum of 9 years before they can become free agents. I say "minimum" because they have to be on the top team roster so many days a year, and many start off on the farm team or suffer injuries, not qualifying for free agency until their 10th or 11th year.

Furthermore, the assumption that teams are just looking for a big payday, like Seibu and Hanshin got this off season, is simply false. The Giants, for instance, don't even recognize the posting system and would rather pretend that they're in control of everything (see the Matsui-Yankee deal).

If any team is going to post somebody, it'll be the year before they become a free agent, which will mean anywhere from 8 to 10 years for most players. The teams will do this out of pride, out of spite, and/or out of utter foolishness. But it is highly unlikely that you're going to see a super-star player posted before then.

Note: The players are trying to reduce the time to free agency. While current talks suggest that this may happen for domestic movement, the teams are looking for a way to at least keep players within NPB for a minimum of 9 years still - so that free agency doesn't apply to moving to the MLB. If/when changes are made to free agency, some or all of the above may be rendered moot.

Generally, I agree with Westbay-san, but a team might think a player (especially a pitcher) has had a career year that maximizes his value, and if he's within two or three years of going anyway, they might look for the big payday. A lot of things would have to fall into place for that to happen, so unless the wait to free agency (and to leave NPB) is reduced, anybody signed by an NPB team has 8-10 years to put in that system before MLB is a possibility.