该……了 is the most common structure in your case. 该走了。 该吃午饭了。 该睡了。

Tiezheng Han, 谢谢！

nonono, you can't say time 时间，you could say 时候. it's the most commonly used form of spoken mandarin , and sounds nature. " it's time to do something"= 是时候do something. Yea, sounds very natural.

谢谢你们！

到时间出发了 到时间吃午饭了 到时间上床睡觉了 到-to, 时间-time