A lot less time than the legal battle, that will start shortly. Matter. Of fact I think the nature crowd file their first case a few days ago. http://www.huffingtonpost.com/2011/10/05/groups-sue-to-block-construction-of-keystone-xl_n_996075.html
Also, the Canadian oil company will pay for the construction and later service on the pipeline, not US taxpayers. The construction will use American employes as will the service jobs. The pipe will be bought from American mills as much as possible. It will be a shot in the arm for our economy.