Sewing on flannel

I know your supposed to wash fabric before sewing but I never wash it. I like the way it is when it's still starched. LOL I love pajamas when they are just made and look new not washed alrea

Yes, you can wash it after you sew...but remember that flannel is cotton and will shrink some when washed.   
It is usually in the length so allow a little extra when you hem them.  I usually allow an extra 1/2 inch. 
Besides children seem to grow in the spring.

Yeah, I agree, I would oversize so when washed they will shrink to the proper size.

Just a comment - whenever I sew with flannel, I need to cleanout the sewing machine more often.  That fuzz gets underneath in the bobbin area and causes it to tangle up the bobbin thread. 

Personally, for PJ's I would probably wash it to pre-shrink it - then I would iron and starch it.

It is a nice effect on a quilt when the flannel pieces all shrink up in different directions and different amounts.  That makes the quilt seem so cozy.
PJ's - maybe not so much if the pieces shrink in different directions.

Flannel does shrink a lot more than regular cloth fabric.

I was warned when planning to sew with cotton flannel that it doesn't just shrink - it's a "progressive shrinker" so I washed mine three times before cutting.  And YES flannel fuzzes up a machine every bit as badly as fleece does.

Sorry, going to hijack for a minute here....you live very near me!!!!  I don't know but one other BYCer in this area