Here's what I know ( which isn't that much). . .
You could have several problems. . but what you need to check for is height of your master cylinder in relation to any line in your system but mainly your brake calipers. Most Wilwood systems are what they call reverse mount or front mount systems, meaning that your master cylinders faces back towards you or away from you respectively. Some front mount systems mount eh master cylinder somewhat low. . . if you have this system, you may need a residual pressure valve to prevent having to push the petal to build up the pressure becuase you can get flow back from the caliper to the master if the caliper or line are higher than the master.
Now. ..if you have light braking until you heat up the pads. . . . may want to look at a different pad compound.
Hope this helps.
Neil