I have learnt that this is the dutch influence on the Indonesian language. Where I live in Australia we say 'half past' where as in Holland and Indonesia its 'half to'. So half past eight is half to nine eg setengah sembilan
While in English it's common to say "half past eight" and shorten it to "half eight", in other languages the phrase "half eight", means "half of the eighth hour (half past seven)".
(And this is why Germans are always an hour early ;)