Back in the day, Branemark used to wait 4 months in mandible and 6 months in Maxilla. But those were a different species of implants. They had a machined surface. Micro rough surfaces are able to osseointegrate faster. So you can restore those after 3 months. Some companies claim that their proprietary surfaces allow you to restore as early as 4 weeks. In general, I stick to 3 months in good bone quality. For bone sites with contraindications, I suggest waiting an extra 2 months.