What is the difference between 卽 (즉) and 卽經 (즉경)?

卽 (즉) can sometimes mean "then," but it can also have the meaning of 卽時 (즉시), which means "at once" or "immediately." The meaning "immediately" implies present action or present tense, but what if you wanted to use it to describe past action? In such cases you could follow it with the past tense marker 經 to avoid confusion. The past tense would be translated in the verb or verbs that follow.

七(칠)月(월)初(초)間(간)江(강)水(수)漸(점)長(장), 卽(즉)經(경)籌(주)備(비)料(료)物(물), 晝(주)夜(야)防(방)護.(호)

In the early part of the Seventh Month (七月初間), the [Yangtze] River (江) water (水) gradually (漸) rose (長). Immediately (卽經) [the authorities] prepared (籌備) provisions (料物) [and] day (晝) and night (夜) kept watch (防護).