Need some help for black girl hair

Hi all. So my family has two little Haitian girls staying with us and we are at a loss on their hair. I don’t get out much and when I do there aren’t that many black people im around so I have no one to ask.

When they came their heads were shaved.. how long does is need to be before we can get it braided?

And how do we keep it from knitting up so tight?

I know not to wash it every day with shampoo. And to use conditioner or coconut oil to loosen it up some.. bit that’s bot helping much. And I’m not sure if it’s completely accurate?

Help would be much appreciated!