First of all, remember that the smaller the number, the larger the size, so you're talking about going up to 10g, not down to a 10g.
You don't want to stretch more than one gauge size at a time, or you'll have tissue damage akin to having a brand-new piercing all over again. It's often best to wait about two months between sizings to let the skin tissues to adjust to the new size.
Also, remember that you're going to have to be buying new jewelry for each size which can get expensive.