Ah. The timeline depends on when the most recent selection process took place. For example, if there is going to be a selection within the next few weeks then you have most likely missed it. During the next selection process they will check your application and see if you have submitted all of the correct paperwork, if it's all fine they will make the decision. If they need more information they will ask for it and you will have to wait another three months for the next selection. This is the part that takes the time because each time they need more information results in a wait of three months and they usually ask for more information (in my case they asked about the financial details of my employer and a reference letter - this may harm your relationship with your employer because they now know that you are planning on leaving). (6+ months)
If you are successful, they will issue you with an Approval in Principle letter specifying which original documents you must bring along with an invitation letter which you can use to apply for a visitor visa, if you need one. You must come to Hong Kong, with the original documents, within three months of receiving this letter and present them to the immigration department. (1-3 months)
After you have submitted all of your originals you can either wait in Hong Kong or go back home and wait for their final decision. For me, it took a few days but it could take longer depending on their workload. Once they have made their final decision you must approach the immigration department with HK$190 in cash to pay for your visa slip (bring more because the amount may have increased). (a few weeks)
Once you have your visa slip, you have to leave Hong Kong (daytrip to Shenzhen or Macau) and then re-enter, showing your visa slip to the immigration officer. They will then stamp the visa and you are now a Hong Kong resident. They will tell you that you have to apply for a Hong Kong identity card within 30 days and give you a leaflet explaining this process. (one day)