The placement of only in a sentence has been a source of studious commentary since the 18th century, most of it intended to prove by force of argument that prevailing standard usage is wrong. After 200 years of preachment the following observations may be made: the position of only in standard spoken English is not fixed, since ambiguity is avoided through sentence stress; in casual prose that keeps close to the rhythms of speech only is often placed where it would be in speech; and in edited and more formal prose only tends to be placed immediately before the word or words it modifies.
Examples of ONLY
She had been there only twice in her life.
There are only two more weeks until summer vacation.
It's only a matter of time before someone gets hurt.
Do you really have to leave? It's only eight o'clock.