I was in a similar position. I think that it would be easier to find a job whilst you are in HK but there is definitely no harm in sending out your Resume to prospective employers/employment agencies. Try the employment agencies to get a flavour of the local job market.
Worst case scenario - if she gets no job then she can travel, explore Asia, or go home.
I found getting a job difficult because I didnt have a working visa + no mandarin/cantonese. But if your girlfriend has chinese then this should make life easier. Plus she will be on a local contract which means low annual leave

(maybe 7-10 days?).