Of course, Visio's schematic library doesn't have symbols with handles that actually line up with one another, so most people end up designing their own library anyway. There are dozens of good schematic-capture programs in the EDA world, but most of them cannot produce schematics that are appropriate for publication in, e.g., a journal article or datasheet.
The original poster, however, was not asking about schematics, but about timing diagrams. Furthermore, he/she didn't really give anyone enough specific information to actually have any hope of helping him/her.
- Warren