First of all, the question of remittance. If you have an account in the mainland of HSBC, you can use instant wire transfer to get to Hong Kong immediately. As for the ordinary way, it's probably the fastest day and the slowest week.

There is also the question of Hong Kong dollars. You can't remit RMB directly in the bank, because RMB is not a currency in circulation and you can't leave the country. Although Hong Kong has returned to China, it is considered overseas in foreign exchange management. You can only transfer foreign currency to Hong Kong, so you have to change RMB into Hong Kong dollars to remit it to Hong Kong.

Ps: Remind you that China citizens only have a foreign exchange purchase quota of $50,000 per year ~