T.K.
HELLO J.
My son is 10 month now, he also started standing on the crib at about 7 months and I read the same thing, So I took the bumper out, but then after one day put it back on!
He felt weird in the crib without the bumper and he would hit his head against the crib, plus he also likes to sleep on the corners with his head against the bumper, so I rather have it on then see him hit his head against the wood sides.
I would leave it on....
Regards,