Which is what I was planning to ask about next: what is the timeline like following the interview? If things go well, theoretically, could she come home with me?
Neil I see you got married last year in February and I am not too sure when you submitted your documents. An April interview time means that it looks like you are ahead of the average timeline for Hong Kong. That is good news for you. Much depends on when your wife did her medical, as it is critical to see if you have another 2 months to wait for her visa. The medical is good for 1 year and if she passes the interview with a few months before her medical expires, then I can see springtime for her visa. However, if her medical expires, then she will have to wait for a letter from the consulate asking for a new medical.
It took us a bout 2 months before she received her passport back with her visa in it. And from others who needed their spouses to redo the medical, asking for the letter when at the consulate for the interview, or asking if possible to just do the redo ahead of time, has always been answered with a retort - "just wait for the letter"!
If your wife still has time left before her medical lapses, then I am not too sure of the timing or if you can pick up the visa. From what I gather, the policy now is that they mail the passport. I think that only Hong Kong residents have the expedited service of being allowed to pick up the passport with visa issued at the consulate, while mainland China waits for the post.