WASH IT FIRST!!!!!
Let me tell you of the experience I just had last month.
I made a raggy quilt for my soon to be two grandbaby. I did not wash the flannel first. It was crib size. I washed it twice when it was done and when I got it out of the dryer it was way less then crib size. Well what to do now??? I bought a doll and sent the raggy quilt with it as a doll blanket. My son asked why I would make such a nice doll blanket, it should have been a litte bigger so baby could use it!!! UGH!!! I am now making 8 raggy quilts for my grandchildren for Christmas, I washed and dried ALL the fabric!!