Mrs. Duck hatched 3 eggs (5 left) in my waterfall, now swim every day with me. When can they fly to leave?

I was concerned how the ducklings would get out of the pool safely once they went in. So I rigged up a flotation with a blanket that hangs over the water, the mattress and then they climb out of the pool that way. Mom has 5 more eggs in nest, but she's now sitting with them at night near the blanket and her 3 under her, while the eggs sit near by. Will they hatch? They are so super cute and boldly swim all around me when I'm in the pool, mom watches intently but she is now sometimes out of the water, while the babies are swimming around me. They are 3 days old and each day get bolder to get my attention or swim right at me while I tread water, so cute. So how do they safely leave? At what age can they fly?