If you don't have an automatic turner my opinion would be to tip the carton up on its side the long side so it is actually just a 1/4 turn for the egg. From the info I have gathered I believe the results are better if the egg is upright during incubation and not put in the carton after laying on its side for 18 days.
On this past hatch, I wasn't able to use my turner as it is made for chicken eggs and I was incubating geese, chicken, pheasant, duck and turkey eggs. I opted to try the egg carton method during incubation and hatching. Instead of putting water in the water reservoirs, I placed it in a child size cup with a paper towel sticking out of it in order to wick the moisture better and turned the eggs by placing a vhs case under one side of the bator, removing it and placing it under the other side several times a day.
I am very proud to say that my humidity and temps did well and that I had a decent hatch on the shipped eggs.