Incubating question???

[oliviaandjosh4]

I am incubating 8 shipped eggs in my DIY incubator. As soon as I got them in the mail I let them sit vertical big side up in an egg carton for 24 hours to help with detached air cells. They have now been in the incubator for 4 days and I have had them in the egg carton still because most still had detached air cells. I am wondering how long I can keep them vertical without harming them. I tilt them in opposite directions about 3 times a day. I will be candling tomorrow (day 5) to look for development & also air cells. I had read somewhere where a person recommended keeping them in vertical position in incubator for 7 days & that helped increase their hatch rate. I'm just wanting to be safe and do everything right as my last incubating venture was a fail. Any advice is appreciated, thanks!