zhèngshì yìdiǎn de fànjú lǐ, zhǔrén shuō "dàjiā chī ba" jiùshì kāidòng xìnhào

正式一点的饭局里，主人说“大家吃吧”就是开动信号。

At more formal dinners, when the host says 'let's eat', it is the signal to start.