One of my duck eggs is on day 22. It's air cell is abnormally large (it's taking up half the cell) The duckling appears to have internally piped...and it whole head its out! I'm almost certain that the duckling is in the wrong position as it has no room to move and wasn't ready to pip. I do have my ducklings hatching around day 25 anyway as I can't change the incubator temperature! So... I know I'm going to have to do an assisted hatch... But when should I do it - how long before he runs out of oxygen?!