Like David says, a lot depends on the method of enriching the fissionable material.

Iraq had a lot of programs for enriching uranium going before the first Gulf War. Most, if not all of them were destroyed, or dismantled by U.N. inspectors after the Gulf War.

However, trying to figure out how long it would take to refine enough fissionable material to build a certain number of warheads is not that productive.

Frankly, I find a more viable threat (and not just from Saddam's regime) to be the construction of a nuclear weapon from already-refined fissionable material, either stolen from stockpiles or purchased from rogue nations already possessing a refinement capacity. Making a warhead under such conditions does not require the large facilities needed for enrichment. You could do it in a large machine shop, with proper precautions.