Zeev, you've just described my "most likely" scenario.
Bush needs the afterglow of a successful war to be much closer in time to the 2004 election. He recalls that his father had 90%+ approval ratings at this time in 1991, benefited by the successful campaign against Iraq. ...and 20 months before his 1992 election loss.
The most likely plan is to be "reasonable" and let the UN, Saddam, etc, have more time. Presuming Saddam doesn't do much to demonstrate further disarmament, the Fall of 2003 becomes the perfect time to start a war and reap the benefit in the 2004 presidential campaign.
Regards,
phill