They're leaving in early September, around the 5th or 6th.
他们将在9月初离开，大约在5日或者6日。
A So when are you back in the office?
A 那么你什么时候回来上班？
B Well, I'm back for meetings on the 28th and 29th.
B 哦，我回来参加28日和29日的会议。
A What about your friends?
A 你的朋友们呢？
B They're leaving in early September around the 5th or 6th.
B 他们将在9月初，大约5日或者6日的时候离开。
A So you're not back full-time till then?
A 这么说直到那时候你才能整天来上班？
B No, but call me any time.
B 是的，但是在任何时候都可以给我打电话。

Notes注释
1 If you know exact dates, you can say, for example: on the 28th and 29th / on the 28th and 29th. / Here, talking about meetings: I'm in for meetings on the 28th and 29th. / I'm in for meetings on the 28th and 29th.
如果你知道确切的日期，你可以说，例如：on the 28th and 29th /在28日和29日。这里给出的日期是会议的日期：I'm in for meetings on the 28th and 29th. /我回来参加28日和29日的会议。
2 If you are not sure about dates, you can say around: around the 5th or 6th / around the 5th or 6th. / and talking about a month: in early September / in early September. So talking about friends leaving: They're leaving in early September around the 5th or 6th. / They're leaving in early September around the 5th or 6th.
如果你对日期不确定，你可以说大致的日期：around the 5th or 6th /大约5日或者6日，或者谈论月份：in early September /9月初。可以像这样谈论朋友的动身时间：They're leaving in early September around the 5th or 6th. /他们将在9月初，大约5日或者6日的时候离开。

Key phrases and sentences
So when are you back in the office?
Well, I'm in for meetings on the 28th and 29th.
What about your friends?
They're leaving in early September around the 5th or 6th.
So you're not back full-time till then?
No, but call me any time.

那么你什么时候回来上班？
哦，我回来参加28日和29日的会议。
你的朋友们呢？
他们将在9月初，大约5日或者6日的时候离开。
这么说直到那时候你才能整天来上班？
是的，但是在任何时候都可以给我打电话。