breaking in the pads: essential before starting your ride
You should try braking quickly a few times on a dry, flat, obstacle-free surface. 3 or 4 sets of 10 dry, intermittent stops are enough to break in your pads. Dry braking will wear down the pad a bit.
Release your brakes for a few dozen seconds between each set of stops in order to let them decrease in temperature before starting a new series of 10.
Be careful of glazing
If the problem persists despite several short, dry stops, lightly rub your brake pads with sandpaper.