The parliamentary battle of our age, and of many ages - over how and whether the UK Brexits - begins, with the signal from Downing Street that the Commons will rise some time between September 10 and 13 and will return for a Queen's Speech on 14 October.
This will leave MPs with just a few days in early September and in late October to block the no-deal Brexit many of them fear.
Which shows a certain sense of humour.
But another No10 source added: "The new Queen’s Speech will be about an agenda for improving the NHS, helping police fight violent crime, stopping violent criminals getting out early, investing in science and infrastructure, and attacking the cost of living with aggressive tax cuts and other measures".
Which is doubtless true, and allows Johnson to claim this would be a suspension of Parliament for a legitimate purpose, namely to pave the way for his government's new programme of legislation.
But the length of prorogation or suspension will fuel widespread concerns about how little time MPs would have to either attempt to legislate to force the PM to ask the EU for a delay to Brexit, and thereby block a no-deal departure from the EU on 31 October, or to organise themselves sufficiently to throw out Johnson as PM via a vote of no confidence in his government.
The bloodiness of this battle is not to be under-estimated.
A No10 source told me: "If MPs pass a vote of no confidence next week, then we'll stay in No10, we won't recommend any alternative government, we'll dissolve Parliament and have an election between November 1 and 5 - and that means no time for legislation."
Against that backdrop, the decision to announce big increases in spending on health, police and schools in a spending review next Wednesday looks like a pre-election giveaway.
And No.10 - Johnson and his senior aide Dominic Cummings - have astutely (some might say cynically) framed the giveaway as a spending review rather than a budget, so there will be no new forecast from the Office for Budget Responsibility of the impact on economic growth, GDP, our prosperity of the no-deal Brexit that now looks probable.
What is increasingly clear is that Johnson and Cummings have a huge advantage over those in Parliament who oppose a no-deal Brexit, in that the PM and his aide have a single ruthless command structure whereas the opposition is disjointed and disunited.
It is striking how effectively Johnson and Cummings have prepared the ground.
As I mentioned they are confident they have gone through all the important constitutional niceties in preparing to suspend Parliament for a month, prior to laying out their legislative priorities in a Queen's Speech, and they don't believe MPs or the courts will be able to stop or block them.