I'm not sure there is a definitive answer to when your away rotations should be done. Generally, most programs start looking at applications to start interviewing in October/November, but some don't decide until December. The first date to fill out your ERAS app was August 15th this year, and the eariest date to submit was Sept. 1. I don't think there is any advantage to wait, so get your application in as soon as possible, even if you don't have all your LOR in yet. I think the absolute latest away rotation you can get a LOR into your app and still have most programs review them is October. It is easier, and in my opinion better, if you just bang out your aways in the beginning fo the year in July, August, and September, perhaps with a week of vacation in between each.