Is it better to convert us dollars to hk dollars before I get there or after I get there?

I am in South Korea. I am going to Hong Kong. I know that it is sometimes hard to exchange won outside of Korea. So, I exchanged won for us dollars. Now what? Do I try to find hk dollars in South Korea or wait till I get to Hong Kong?

You usually get a better rate when you withdraw funds from your bank account via a ATM (bank machine, auto teller...whatever name they use in each country) in HK, even after you add up the transaction fee charged by the bank and the network.

I don't think US$ would be best in Hong Kong. US$ may be OK in markets but not sure about normal shops, restaurants, attractions etc. If you have a credit or debit card there are numerous ATMs, best at banks, where you can withdraw in HK$ for a small fee. Can you buy HK$ from a bank in Korea, might be the cheapest way. Enjoy your stay. If you like jazz go to Cafe Deco at the peak and have a pizza, best at 8pm for light show. You may have to book for a good seat/table.

get it done in korea if possible

Why you changed your won into US$ first? US$ is not as good as you think. You can actually exchanged you won to HK$ directly in both South Korea and Hong Kong respectively. Just for exchanging won to US$ and than US$ to HK$, you have lose some money just by the exchange fee and you can have less money to spend than exchanging directly from won to HK$. Since you exchanged your won to US$, exchanged it in Hong Kong is better as its the straight conversion rather than in South Korea. If you still have won, exchange it to HK$ in South Korea straight and don't do it in Hong Kong, as the rates are poorer in Hong Kong Than South Korea.

Not at airports- their exchange rate is higher than the bank

After you get to HK, the rate is alot better!