I have tried to make a text object invisible until about 1/2 way through my animation.  I have selected a time on the timeline and set "invisible" in the prop manager, then later on the timeline I have set the prop "visible" on the prop manager, but this did not work.  Can this be done with text?  If not, would a mask help me hide the text until I wished it to appear?  I have not used a mask and would need instruction if that is the way to accomplish this.  Help, anyone?

Visibility works the same way regardless if it's a prop (I assume your text is a prop seeing as there is no real text in the application) or a set piece, or a character. On the main stage, top menu bar press the Visibility button to either Show or hide your prop. Or you could set the Opacity level. Move down in the timeline where you want you object to be displayed, put a keyframe right before the frame you want to show your item (to prevent tweening), go to the next frame and make your prop visible with either hitting the button on the top menu bar or by adjusting the opacity value.

I'm not exactly sure what you mean by "prop manager", but as long as you're doing this all in the main timeline on the main stage, and not in any of the editors (character editor, prop editor, etc...) it should work just fine.