No need to overthink this or make it too complicated. Put them on at 5 am. cook them at 250 until 12pm. (should be around 165 internal temp) Give the butts a glaze of your bbq sauce at this time and wrap tight in foil. Depending on your timeline, you can keep it at 250 or crank the temp up to 300. It will make absoultly no difference in your end product. take off when butts probe resistant free around 195. Before letting them rest in a cooler, let them steam off for a good 1 0 minutes. Then rewrap and put in cooler to rest up to 4 hrs. Pull just prior to serving. Putting it on at 5 am also will let you keep a close eye on the green egg assuming you dont have a guru or stoker. I would put one finger width on the bottom door and 20 percent open on the daisy wheel.