A good rule of thumb is 30 days from the time you transferred from primary to your secondary and placed under airlock. But, you also have to look at what you used to make your wine. For example, if you are making a chocolate wine & using cocoa powder you will notice a thick fudgy layer of lees developing--you rack sooner than 30 days because the layer is getting quite dense. If you use all juice you will have finer lees vs. using fresh fruit in which you can anticipate a bit more particulate (but again it will depend upon what fruit and the method you used in primary [straining bag, no strainer].
Don't rely upon bubbling--use your hydrometer to check for activity.
Motto: quel che sara sara