星期六晚

昨晚琴晚／尋晩 我同朋友去咗食飯。我好遲返咗返到 屋企所以現在依家 我真係幾攰。

When you talk about 'yesterday' or 'last night', you use 琴(Kam4)日 ／尋(tsam4)日 or 琴晚／尋晩,

'昨'晚 is the written languge in Chinese :)

我好遲返咗屋企 

咗 denotes the action you're talking about is already done, and sometimes it implies that because you've already done that something, you are or are not going to do another thing that's related to that action. That sounds a bit complicated, so here is an example:

Scenario - Your boss calls you after work thinking you're still in the office. He asks you to look at a contract on the office computer or whatever, and you reply with:

"我返咗屋企啦喎。"

What you're saying is: I've already gone home. 

What you aren't saying but implying is: Don't bother me with office work now (becasue I've already gone home). 

In Chou's comment above, she's used 返到, which is also correct. 到 means "arrived already" here and has a spacial denotation; I think it's kinda like "bis" in German. Let's say you're going home from your mom's place and it's already very late. She calls you just when you get home. She says, "返到未呀？" ([Have you] Arrived yet?) And you tell her, "啱啱返到啦。" （Just arrived.) And what you say is simply what you mean there. 

Hope that makes sense!

星期六晚

琴晚我同朋友去食飯, 我好遲先返屋企, 所以而家真係幾攰。

星期六晚

尋晚我同朋友去咗食飯。我好遲返咗屋企，所以現在依家我真係幾攰。

(昨晚我與朋友吃飯。我好遲回家，所以我現在感到很疲倦。)

Sehr gut!