It's actually easier to just include the count-in in the first wave file, then Open the Wave file in RB and Cut it (using Close Gap).
Then rerender the new Wav, making sure all sliders are up (so you don't inadvertently lower the volume)
This also gives you a chance to adjust the volume on the final Wav file.


I do not work here, but the benefits are still awesome
Make your sound your own!