It would be very helpful if after a user installs your app and is redirected to your app's canvas page, a parameter was passed along indicating that the user has just installed.
This would make it much easier to show "Just installed" content to users without using error-prone heuristics as is currently the case.
It doesn't really matter what the param is called as long as it's constant. just_installed=true or whatever else you want.
Thanks.