How do you say

I’ll come to Beijing for a conference in a month. Will you be around then?

..in Chinese?

我一个月后来北京开会,你那时有空吗?

wǒ yí gè yuè hòu lái běi jīng kāi huì , nǐ nà shí yǒu kòng ma ?

How do you say "They will finish the project in three months." in Chinese?