I don't think there is an age limit for a Cougar ...
Wikipedia describes the slang term as follows:
Cougar — an older woman who sexually pursues men at least eight years her junior,[11] coined in western Canada[citation needed]. The term has been used in TV series, advertising and film. The 2007 film Cougar Club was dedicated to the subject and in Spring 2009 TV Land aired a reality show called The Cougar.
Therefore a 32 year old would be a cougar to anyone less than 25 years old. I suspect that the general usage is more for Gals over 35.
The defintion of MILF is very much the same. If a 32 year old has a child she could technically be a MILF but we normally associate the term with someone older.
My two cents ... T