I'm going to have to politely disagree with this. I think there's very little use sticking cars haphazardly on routes all over the system. Just think about it, if there's only 2 new cars on Queen or College routes...the expected time between arrivals would be well over an hour. I don't think anyone is going to sit around and attempt to plan on the arrival of the one accessible streetcar. Also given the quality of the TTC's line management, I would not be surprised to see the two accessible cars end up following one behind the other...indeed that often happened on Spadina in the early days with the poor blending of the service branches.
Much better to convert the lines one or two at a time. Then riders can consistently have the expectation of seeing an accessible streetcar with some regularity, i.e., they're willing to wait one or two streetcars but not an hour and a half.
As for the order, I'm puzzled why the 511 is next...I would imagine the biggest bang for the buck would be to concentrate on the highest ridership lines like 504. 511 doesn't seem to have anywhere near that level of ridership.