The second that Iran enriches beyond 70% or so, the resultant radiation will be measurable across the globe. Measurable in labs run by military and civilian labs.
The fact that this has not come out means they are stockpilining the low grade uranium. But not moving forward. And they won’t.
They just want to keep oil up so they can get some hard currency.
You will see a different tone as soon as this changes. Not different words, but different tone of conversation.
That assumes they intend to build a Uranium bomb.
But they could take that 20% stock and put it in a reactor...and then extract the plutonium from that.
You can't detect that stuff across the street.
But even if they intend to build a uranium bomb, they could have everything ready...triggers tested...case...delivery/bomb mounts etc.
Then they can start converting their stock to HEU 235.
How long depends on how many resources are applied. Somewhere between a few weeks and a few months.
Given the "diplomatic challenges" it's unlikely the world could react that fast.