They figured it out pretty much immediately. I just "pecked" it a few times with my fingers, and they got curious. Once one figured it out, they all did.
I bought a bucket with a lid at TSC (it's not a 5 gallon bucket, though that would work, too). I got the nipples off Amazon. I just have one bucket with 4 nipples, but I may get another. Dark colored buckets inhibit algae growth. I fill it up once a week or so and make sure the nipples still work. It's never even been dirty inside, and I've had it for 4 years, I think.
I also have the 2 duckie buckets that the chickens sometimes use, as well as a traditional gravity waterer. The gravity waterer gets VERY dirty, even though it's raised, but I like to give lots of options, esp in the summer.