Indicating is to show others that you are changing speed or direction, moving within your lane is neither of those so I don't signal.
It is my lane and I ride on it as far to the left as I feel is safe. I don't have to explain or justify that positioning to others just because they happen to be in cars. That applies whether or not my cycle has a motor, the full width of the lane is mine.
That's the way that I do it and I've never had any problems with taking primary. I think a lot of it depends on the rider being clear and confident in assuming their road position.
It's impossible, IMO, to tell others where and when to do it, though, as it is entirely dependant on local circumstances at the exact point that you are there. When I move across going up hill is later than going down hill, junctions change things as does weather, traffic density, road widths, pedestrians... etc.