This is the way I've done it in the past:
Create a fade animation and have it fade from 100% to 0%. The length of time doesn't matter much, you can make it as short as you want. Move the work area start marker after this fade. Then you should be able to do your fade from 0 to 100% whenever you want. I think this is a bug they plan to address in a future release, perhaps in 9. I seem to remember a post about this, but I can't find it right now.