Walking is considered a safe form of gentle exercise during any stage if pregnancy (unless medical professional has advised against it) your baby will come when it's ready, if it's not ready yet no amount of walking will make it come early.
Walking as in just walking? Trust me just because you walking it doesnt mean your baby is going to be here right away. At 36 weeks I was doing the elliptical every day. I am 40+1 today and been waking on rocks at the beach every day and still no sign of baby. I think you will be safe to walk.