How do you say

I want to buy a new sofa within one to three months.

..in Chinese?

我想买一张新沙发,在一到三个月内。

wǒ xiǎng mǎi yī zhāng xīn shā fā , zài yī dào sān gè yuè nèi 。

How do you say "I'm taking the train to Beijing in three months." in Chinese?