Many new maids (no matter Phillipino or Indo), there is a trend that they deliberately performed badly, and let employer fire her. So that they can get an extra month salary for doing nothing, and while waiting for the contract termination documentation, they could easily find another employer. You can read other posts in BK with similar situation.
My personal experience is that I won't employ oversea maid unless they worked as maid before in other countries. But no matter what, it is not easy to get a good maid, especially many of them could be influence by the agent, and some bad friends.
To fire a maid, by law, you will need to pay her the following:
1. one month salary
2. air ticket
3. transport fee that for her to travel from airport to their home (in their country), usually HK$100 should be ok.
Anyway, good luck with your plan, and actually if finance is not your major concern, you could temporarily get some baby sitter to help out, until you find a good one. By the way, aware the bad agent list!!!