Cairo Speech - then William Ayers and other Marxist 'Organizers" went to Egypt to 'organize'.
You also need to stop thinking like a stupid American and start thinking like a Jihadist. They embrace death. Any 'go' signal is the cassus belli to act. Obama signaling to the Muslim Brotherhood that he would support their ouster of Mubarak (same with Ghadaffi and Assad BTW) is all it took.
As to Islamic prophecy - the Shia have their 12th Imam and the Sunni have their Mahdi. BOTH envision an Islamic global caliphate. They simply differ on which 'denomination' gets to run it once they destroy the Great and Little Satan.
As I recall, the Cairo speech said nothing about Islamist rule, and I really doubt that William Ayers could organize hundreds of thousands in Tahrir Sq given that he failed to do the same at home as a Weatherman. You're giving him far too much credit.
Any 'go' signal is the cassus belli to act.
Islamists have been staging terror attacks and trying to seize power in the Arab world for decades. They've never needed a Washington before and they don't need one now.
Believe it or not, the US doesn't actually micromanage everything that goes on in the world.