There seems to be buses at 6:30 and 7:15 to get you there around 7:45 and 8:30, so I would aim to be ready to be at the bus stop by 6:15am just in case.....if one doesn't show up, I sure the other would.....but if neither, then you still have time for a taxi (which would be stupid expensive)....It isn't common for TWO buses not to show up, but I hope you are going in a weekday, as your options are greater :)
There are at least bars near the station that will probably be open by then, if not the one in the station will definitely be open to get a breakfast snack....
https://www.sitabus.it/orari-sita/orari_sita_05120_AMALFI_-_MAIORI_-_SALERNO.html#google_vignette