It matters a lot how old the plant is. A 1 year old plant with healthy roots will be fine. It it isn't much more than a rooted cutting, then it will take a lot less stress. Ship on Mondays. Water well (soak it) the day before shipping and then top it off just before packing.
I have had 1 year plants go across the country in the summer, and get returned - so gone for 12 days, and they were still fine.
It is all about plant age, and maturity, and how careful you are.