Usage of 就 in these two examples I'm taking an intermediate Chinese course and ran across a character whose usage I can't quite wrap my head around: 就.

I believe the meaning of the character itself are "then, right away, etc." However, I'm finding it difficult to really understand the usage from just the definition itself. Here is an example from the textbook I'm using:


等你来天津， 我就给你当导游。 (When you come to Tianjin, I'll give you a tour.)
等你来天津， 我给你当导游。(When you come to Tianjin, I'll be your guide.)


How should I interpret 就 in this context?

Thank you.
[等 (X) 就 (Y)] = [wait till (X) then (Y)]


Example:

等(你来天津)， 我就(给你当导游。)

wait till (you come to Tianjin,) I'll then (be your tour guide.)

Other combinations:


  [一 (X) 就 (Y)]  = [once/as soon as (X) then (Y)]


Example:

你一(来天津)， 我就(给你当导游)

Once (you come to Tianjin,) I'll then (be your tour guide.)


  [如果(X) 就 (Y)] = [if (X) then (Y)]


Example:

如果(你来天津) 我就(给你当导游)

If (you come to Tianjin,) I'll then (be your tour guide.)