Candle them. Just don't use your hands. I know (with canaries!!) that viable eggs are visibly viable after the first 3 days, so with a 4 week gestation I'd wait at least a week or two weeks to start seeing the spiderwebs. I used a single LED flashlight w/a flexible neck for the canary eggs.. I would use one of those 9-LED flashlights to penetrate through the thicker shell of a turkey egg. This could be exciting!!
