幾時可以換永久居民身份證

Unable to answer.

The *** from HKID represents you are 18 years old and have the right for re-entry permit.

So unless you are 18 years old, or you don't have restricted condition in Hong Kong (like you are a Permanent Resident), you will get it by then.

2012-09-04 15:00:31 補充：
There is a separate process that the Immigration Department must verify that you are eligible for a Permanent Residence. If so, the new ID will be issued at the same time.

你就等下輩子吧。。。