How long did it take the United States to obtain enough highly-enriched uranium, using 40’s technology, to build the bomb we used on Japan?
Iran does not have the resources to recreate the Manhattan project or design their own modern refining equipment. I doubt they can physically construct a working modern bomb even with uranium in hand.
They can build a primitive bomb but are 100% dependent on imported technology to build it. Unfortunately, humanity typically has no shortage of members willing to sell out to the devil.