Kwei Mensah

Try and be there not less than 2 weeks before your interview date , that's the most important thing . They will tell you when you can pick it , most of the time a day before your interview. 

We received ours the same day. It must vary from person to person. 

changing of embassy is going to delay your case. what sort of visa ?

i had to go to your profile to see type of visa as you don't say here
for your CR1 i can not answer if you can get the interview in China
but what of your criminal report ?   
you able to get one from Ghana?
you live in China now and able to get one there?
 
an opinion only:    seems like asking for a change of embassies would cause further delays

They typically schedule in 90days. My husband waited about 90days before getting his interview 

Ghana has been running behind on a lot of things lately so yes your still in the normal waiting period. My fiancé had his interview November 16 and was approved and we are still waiting to get his visa.

The letter I received from NVC stated that most interviews are scheduled within 3 months.  I don't think you are beyond the normal waiting period at this point.

Your notice of interview will be by email from NVC.  Expect it any day.  Accra does have a history of backlog though, so it might be up to a few weeks more before you know the date.