From what i have read on here before, yes you do a large water change and 'fully' stock your tank as the bactria you have built up using the fishless cycling method means there are enough bacteria to cope. If you under stock your tank, you will start to lose some of that bacteria. As i said before, i am not 100% sure but thats the gist of what i understand of it.
GRJ is correct. 90-100% waterchange, adding declorinator as you fill. Dechlorinator works instantly. Make sure you add water at the correct temp though, or you may put your filter bactiria into temporature shock. I belive this makes then dormant, thus absolutely useless when you add fish. You can stock fully strait away. Just remember to top off the stocking slowly, if you don't fully stock your tank, as the bactira built up will die off whithout a full bio-load.
HTH
rabbut