angry mama ducks, have sharp bills! So don't eat their babies, balut or otherwise!Just wait till they pip!!
So bring a flashlight...
A suggestion ...bring a big calendar or make a grid with mama duck on nest at day 1 - use tally marks for numbering each day 2 thru 30. Go to live balut and ask by drawing a qustion mark on say the 3 sets of five talleys (15 days?). Store person can indicate yes or no. Proceed until yes. Then go to the fridge eggs and get him her to point at your page. Then you have idea how long eggs are in unbought live before they get cooked.
Beware you could get abnormal ducklings if they were cool too long. Sorry.