the problem wasn’t timing imho. It was strategy. Rumsfeld was a advocate i think of light boots on the ground. He wanted to balance security with sensibility of the resident. He was concerned we might look like occupiers with so many troops in the city and on the street. The troops basically went in, hit a few spots then left
Petraeus took a diferent approach. Massive surge of troops into trouble spots and they stayed and lived there
See #10.