The Preparedness Movement started in the US as WW1 started and gained considerable momentum with the sinking of the Lusitania in May 1915. The Movement wanted to introduce conscription of 600,000 men annually and maintain a large standing army in peacetime. After a year of controversy a compromise was reached in May 1916 to double the size of the Army to about 220,000 men and drastically increase the size of the National Guard, this was signed into law in July 1916.
Given the huge disparity between the Movement's aims and the compromise what if this controversy was sorted out much earlier, perhaps the 1916 compromise could have been made in November 1915? If the US Army had been expanding for over a year in early 1917 would the Germans have started unrestricted submarine warfare? Would this make much difference to the AEF on the battlefield?