Like those who've taken the time to review this route, I also have a sneaking suspicion that it doesn't really exist...or not when you need it anyway.
In all the times (which, I'll admit is not as a daily commuter on the route) I've waited for the streetcar on King, I would say only 10% of the time has it come in a reasonable amount of time. I waited at King and John for 10-15 minutes around 8 pm recently and couldn't see one coming, so decided to walk to my stop (Bathurst). And just as I got to the busy King/Bathurst intersection a car finally passed me...swiftly followed by 3 more. And that, I find, is most often the trend on the 504...you'll wait forever but when it does show up, it brings friends.