you can wash your fabric as often as you want- it is yours----no one will have any idea if you washed it once or a dozen times...as for the ironing---if it comes out very wrinkled and you feel like it- iron it before refolding- if you can smooth it nicely (enough) to fold you can wait until you are going to use it- if you choose to iron first i would avoid sizing or starch if it is just going to be stored on shelves for more years---if you need - something- to help with the ironing-a spritz of water is generally enough.