Cloth diaper sizing advice?

It is doubtful that your child will outgrow the bumgenious by age one and it is very, very unlikely that he will gain 10 pounds in two months. He sounds like a pretty average sized 10 month old, and bumgenious diapers are designed to last from birth to potty training. I know average sized 3 year olds that wear them, and if my own 3 year old was in diapers he would still be wearing them on the second setting. So I think you will do fine with the bumgenious.