make the quilt first- then wash it.
if you try to clean the blocks before the quilt the edges will fray- the blocks may shrink- they may become un-usable- make the quilt- when it is all done= quilted and bound- wash it- pre-treating the stains in necessary- if it is for a child you want it to hold up and be washable- so when it is done treat it as if it is to be used, washed and dried.