It's safe to bottle after you have several days of the same hydrometer readings. Even then I would wait at least 3 to 4 weeks from pitching before thinking of bottling.
Yeast can't read a calendar so hydrometer is the only way to go. I leave all my beers alone for 4 weeks before I even think about secondary or bottling.
This is the first time that I have used a yeast starter and brewed a higher gravity beer. So maybe I was just used to the lower gravity beers that I was brewing, which would be ready for bottling in two weeks.
Even with lower gravity beers, you don't want to go to secondary until it's reached it's FG and is stable. You can stall the ferment if you transfer too early. Have you checked what the gravity is now?