My DS started ballooning fairly young. Not as a newborn, but well before a year. He's not retractable yet at age 6. Two things need to happen to become retractable. One is that the foreskin needs to detach from the rest of the penis. And the opening of the foreskin needs to become loose enough/stretchy enough to open up so it can slide back over the glans. These things can happen in either order, within days of each other or years apart. Some boys are able to pull the foreskin back partway, only to find that they still have pieces of the foreskin attached. Some boys balloon fully (indicating the skin is entirely separated) before they can pull it back over the glans.
I don't think when a boy starts to balloon has anything to do with when he'll become retractable. Ballooning is quite common in early childhood, yet the average age of retraction is about 10 years. So it seems to me that ballooning as an indication that the child will be retractable soon is a misconception.
Follow Mothering