Hi! You've come to the right place for this question. There are many ways to deal with washing fabric!
I'm one of the pre wash fans! If it is a FQ or larger, i serge the raw ends and prewash.
If it's a precut, I make the top, serge all 4 sides and prewash before I sandwich and quilt.
And I always wash the quilt when it's done and bound. All washes on delicate, cold water and with color catchers. I use warm and natural batting so I never have to wash batting first.
So find what works for you and go with it.
And welcome to the forum.