Do understand that there is a difference between bring shrimp, which are adults, and baby brine shrimp, which are as stated, babies. You can get adult frozen or fresh if you are lucky at most any lfs.
Freshly hatched bbs requires a hatchery, which is easy enough to make. An old clean plastic bottle, I like 2 liter pop bottles, an air supply, and a light source are all the equipment needed. Brine Shrimp Direct has some instructions for hatching bbs here;
http
/www.brineshrimpdirect.com/res-hatching-c169.html
To make it easy, you are making a high saline solution, with hard water, and bubbling the bbs eggs in this for 24 hours at 80F. The light source provides heat as well. This is why I suggest a test run if it's the first time you are running your setup.
Generally they are eggs for a couple of days, wigglers for 3-4 days, then become swimmers. This goes a little quicker at warmer temperatures, slower at cooler temperatures.