After how many weeks of exposure would the 4th gen hiv test be more accurate than a naat or rna test?

It depends...: Unless the exposure was especially high risk, e.g. unprotected non-oral sex with a KNOWN infected person, NAAT testing should not be done at all. The 4th gen blood tests usually are positive at 2-3 weeks and always by 4 weeks. That's probably what you need. If the risk may have been genuinely high (e.g. unprotected anal with another guy), don't test online; see doc or clinic in person.