2 to 2 1/2 months is good; I did my PPL full time in eight weeks but lost days due to unserviceability of the aircraft (OK, I broke it!) and it was the only one!
The most important thing to consider is where you will be flying once you have your PPL and make sure that you know what has to be done in order to get your licence (obtained in one country) valid in your home land.
The rules vary from country to country but these are not international licences. Usually, one can obtain a licence in one country and then do a conversion in their own country. You will need to look carefully into this. Quite often the costs of doing this negate the savings made in the first place.
South Africa is good - I've flown from Virginia in Durban. Very professional, good instruction, fab weather. But I have no idea whether a South African PPL would be valid in HK.
Cheers
Whirlygig