First, you can stop worrying. A high percentile doesn't necessarily mean baby is overweight. His weight percentile isn't nearly as important as his weight-for-length percentile. If he were also in the 100th percentile for length, for example, his weight-for-length percentile would be considered pretty average.
Even if baby's weight percentile is quite a bit higher than his percentile for length, keep in mind that your child is probably at the fattest time of his life. Most breastfed babies thin down from six to 12 months.
Try to forget about the scales, and focus on baby's activities instead. Allow him lots of time for active play on the floor, encouraging him to move those tiny muscles. Before you know it, baby will be on the go, burning calories at the speed of light.
And definitely don't try to limit baby's feedings. Instead, opt for lots of playtime and provide a healthy example by keeping your own activity level up and eating nutritious, well-balanced meals. As you start baby on solids, it may be best to offer finger foods that baby can feed himself — this allows him to totally control his own intake. (It's tough for a parent to know when baby is full.)