As far as I know, the policy hasn't changed.
This is anecdotal, but I've heard there were problems with wait list kids not being invited to open spaces in 1st grade last year. Apparently there was some kind of miscommunication between the school and the immersion programs office (the degree to which this was actually a "miscommunication" is the subject of a lot of rumors in the school, but I don't know if there is any real basis to those rumors).