The water test works great or just setting them on a granite countertop. After 45 days they will start moving a lot. It not just rotating to one direction. Also try whistling why you are watching. They will usually respond by moving.
Good luck
a little update.
The Ostrich has started changing postition in the egg, Basically when I candle the air sac has moved from the front of the egg to the top. I hope that makes sence. He also responds to whistleing, tapping by wiggling like an emu. Only a couple more days.