Ranhou simply means First A, then B. Simple sequence in time. You will hear this phrase very, very frequently. Do not abuse it. It is somewhat juvenile and overused by the less educated. Think about a kid repeating a sequence of events by prefacing each sentence with ‘and then’…
The use of ‘jiu’ and ‘cai’ are a bit more nuanced.
‘Jiu’ means that something happened sooner than the speaker expected it too.
‘Cai’ means that something happened later than the speaker expected it.
These are important usages to get a handle one because they are used constantly.
Actually, I didn’t mean those pronunciations are used in China. I mean that they are part of Taiwan’s largely imaginary standard for Mandarin as established by the Committee to Promote National Languages and codified in textbooks and dictionaries. I suspect they are used somewhere in China but they are not part of the Hanyupinyin standard.
The main point is that you just don’t hear those readings very often in real life.