I start them swimming asap. I give them a day to settle in and then I let them swim.
I start with a small thing of water - this time it was the sink - they really just needed a bath.
Dill was diving in the sink the first time. Jasmine needed encouragement, but she was itty bitty and gross.
The next day I had water in the little pool and they could still reach the bottom, barely.
Then I added more water. Then it rained, so water was deep. I just do supervised swim times until I am confident they can get in and out on their own.
Before 2 weeks they knew in and out, but seemed to have forgotten at the end of this week. Jas figures it out, Dill needs help in. Out they have no problem now.
They've also taken lots of dips in the big girl duck pond and can get out of that on their own as well.
If it is chilly out, I get them back under a heat lamp to dry. If it is nice out, they stay out in the sun.
Mine are almost 4 weeks and hang out on the deck for part of the day with their pool. I'm somewhere near by - house or yard - when they are on the deck, so I keep an eye out or ear for the diving.
This week they will move to the yard fenced in a small area (about 12x12). I'll add their pool in later in the week once they've gotten a bit bigger.
I'm not going to spend my time watching for the ducklings to swim. That's the mother duck's job. She can take them to water and watch them herself, as her kind has been doing since OUR kind were still pre-human hominids. We have only had two ducklings drown, that's certainly an acceptable rate.
Mine were two days old the first time I had them swim. I used warm water, and dried them with a blow dryer on medium and a towel. They loved it! So cute. I think I'll put them in again tomorrow, they'll be 5 days old! Yay! So much fun. Also, watch them very closely as they can get waterlogged quickly and that's not good.
@Mashall, I think she's brooding them herself....it's different if the mother duck is brooding them since they get the oil from her.