I most likely agree with you, except I think we do this a little differently:

you shouldn’t even be starting to signal if there’s not room.

I disagree with this because I think it’s better to signal your intention to change lanes as soon as it’s practical to let others know. For example, if there is heavy traffic and I need to get over, I’ll put on my blinker and wait for my safe chance to merge. That way the person behind me knows why I’m slowing down, and the cars to my right can either speed up or fall back, if they notice at all. I may have to wait until it’s safe to change lanes, but I’m being courteous to those around me by signaling my intention.

The only time I wait is if there is a single car passing me: I’ll wait until they pass before putting on my signal, since I don’t have to wait long, and that car might misinterpret my signal as a warning :p and slow down. If it’s multiple cars passing, I’ll put on my signal so people can predict my actions: that I’ll change lanes at my first safe opportunity.