The sign on time issue effects my airline as well. If I want a cruisey day where. I'm not late from the get go I have to turn up early, if. I don't then we can't get off blocks on time and we end up missing slots and getting mucked around.
Much paperwork has been submitted, nothing changes. The problem I have with turning up on time is that it makes my life harder and doesn't seem to get any sort of message through when the flights get delayed.
The only way I can see it being effective is if we all turn up on time rather than early but that would require coordination which is basically illegal where I am.