Wait until you get them than you worry about even more. Are they warm enough? Too warm? Are they eating? Drinking? Is that one dead? Oh, thank goodness it's just sleeping. What about that one?
No matter how many times I order I always get a bit stressed for the first 2 weeks. Make sure your brooder is a good temperature.Check with a thermometer. Make sure there is some electrolyte in the water the first few days as they can become depleted and have low blood sugar on arrival. If you don't have chick electrolytes than brown sugar can work, 1teaspoon to a quart of warm water. Also make sure to keep checking for poopy butt. I also put in some glass rocks in the water, and feed, and scattered about to give them something shiny to peck at instead of each others eyes.
The rest you can't control. Some unfortunately don't make it, but most do. Looking forward to seeing your new arrivals.