jiù (就) typically marks a simple focal point, linking an Antecedent with a Consequent.
→ 你去我就去 (n˘ı q`u w˘o ji`u q`u/ I will go if you go.)
In certain context, jiù (就) can be used to underline the imminence of an activity, implying the event will happen earlier than expected.
→ 他明天就來 (t¯a m´ıngtian ji`u l´ai/ He is coming tomorrow.)
Reference: Chinese: a linguistic introduction by Chao Fen Sun