Can I enter Hong Kong with employment visa before the official duty starts?

Hi,
I got a job in Hong Kong and plan to obtain an employment to enter Hong Kong. I wonder how soon I can enter Hong Kong with the entry permit. For example, if the employment starts in April 1, can I enter Hong Kong sometime (like a week or two) before April 1 so I can set up my life and prepare for the work?
Thank you in advance,
YN