What pads have you fitted? If they're a performance compound they may take longer to bed into the discs - depends on the composition.
Either way, they'll need properly bedding in. Start off with fairly light pedal pressure but don't tickle them. You fairly quickly want to be braking fairly firmly but not for long periods.
If you mince about with the bedding in process (a lot of people are worried of overdoing it) the pads will glaze and never work at their optimum.
If you can find somewhere suitable to follow this procedure, do it; it's the quickest and surest way of bedding pads in properly:
Accelerate to ~50mph, then brake steadily almost to a halt (don't stop entirely).
Repeat around ten times, each time increase braking effort.
On the last run you want to be applying pretty much maximum braking effort.
Make sure you DON'T STOP COMPLETELY using the footbrake, at any point during your ten runs.
After the last run, come to a halt by coasting or using the handbrake and leave the brakes to cool right down.
That's them bedded in as best as you will get. Takes a bit of time and effort but it's your brakes after all, got to be worth it.
Have used this method to bed in new cerametallic and kevlar pads for racing and they do then work at full effectiveness from the word go.
Take a cloth with you and give the car a wipe over while the pads are cooling to ambient temp, give you something useful to do while you're waiting!
HTH
James