the interview is easy anyway.
Suggest you to find a place with internet connection, and make an apporintment online, if the available date for visa stamp is not that early, that's ok, just keep refresh the page, sometimes some people will drop their appointment, and you can pick it up with a earlier date.
for me, I initially made an appointment for three weeks later, then I found a guy dropped his appointment with an earlier date, and I picked it up.
so, keep refresh the page u will get an earlier date.