Hi Mariana, you are totally right!
Just to add some information after what Marcio said...
is a simple way of saying "em dois meses e meio." (do momento em que se está, deve demorar esse tempo para ocorrer).
However, the use of the sentences structured without the word "time" are pretty common:
We will meet again in two weeks.
I will visit her in three months.
You can use the word time after the word with aspostrophe or not.
See the links below:http://forum.wordreference.com/showthread.php?t=909041http://www.theguardian.com/media/mind-your-language/2013/aug/16/mind-your-language-apostrophe
In the second link you can read an article from The Guardian, a famous newspaper, about the use of apostrophe in many cases, right?