WOW the number of threads on this subject is amazing. You will find that there are as many people who don't wash and have absolutely no problems whatsoever (including dark colors and batiks) to those who wash, using various products to prevent bleeding and have horrible problems with various fabrics. Many people wash simply to remove all the stuff that is put into fabrics (can't think of the names) to make it crisper and easier to put on bolts before shipping to stores.
I don't wash my fabric, never have..never will...and have had no problems whatsoever....my life is full enough that if I had to wash it all it would take all the joy out of the process for me. I do iron before cutting.
Just type in washing fabrics in the search box and you will numerous threads and more information/opinions regarding this subject.
Welcome to the Board, and use the search feature...it is a fabulous tool for everyone and you will find valuable information about everything possible. There is NO right or wrong way....just the way that works best for you. :D