If you are an experienced rider, I would not sweat a new bike too much.
About 40 years ago, I flew to London with my camping gear and panniers hoping to land a Claude Butler but had to settle for a Dawes. I bought it one day and the shop had it ready the next. The sense of adventure setting off to the North on a new set of wheels is exciting, especially when each day you do your route finding. Which village will I shoot for today. I rode that thing all over the UK and then the whole perimeter of France. A good shop mechanic should go thru a new bike and make sure the wheels are good and tight. Your timeline is ridiculously short but.....just do it. Get any niggles fixed before passing Redmond, Oregon. Not as many bike shops after that.