You have many options - bring a bunch of cash with you or just transfer it (that's your decision)
I would bring money for:
Covering 3.5 months for the apartment ( how much depends on where you want to live)
Deposits on your utilities (just to be safe assume 1000 HKD per utility needed)
Money for food, transit, entertainment until you are getting a steady paycheck (talk to your HR department and find out when you will be paid and when you will receive your first paycheck)
If your company is providing you with a serviced apartment for a month - that should help you out with the money situation. It's too hard to give actual figures, but things you'll need money for is a lot easier for us to give you advice on.
Assuming you have your apartment situation sorted out for the first month that you arrive (serviced apartment paid by your company) 2000 USD should be plenty to have on hand... and having access to more in a bank account back home... Or parents or friends that will help you out in an emergency :-)
Best of luck!