Ii am one of those that prefers to have my fabric washed before cutting it.
If a design is printed off-grain, one can do whatever to the fabric - it is still printed off-grain.
I am extremely aware of grain lines - some people think grain does not matter.
Do what you are comfortable with.
I lost respect for Sharon Schamber when she said one could "stretch" a quilt block to size. I always wondered what happened when the item was washed.
I remember old denim jeans - they would be comfortable after wearing them a couple of days - next time they were washed, they were very snug again.