As the name implies, you can decide how long you're willing to wait before the translation begins. If you're dealing with closely related languages like French and Spanish, for instance, you could start translation after a single word. When it's a more complex translation, like from Chinese to English, you could tell the system to wait longer and improve the accuracy. Predictive code can anticipate what comes next and shortened the perceived time, although it needs a huge amount of training data to be relatively accurate.
The system still isn't accurate enough to replace human translators when they're necessary. Baidu believes it could make real-time translation more practical, however. As it is, this provides China with a major simultaneous translation option that it might not have given Google's current absence in the country.