The latest you can take the OAT is probably even acceptable after the application deadlines provided that you've taken it at least once before. I mean...if schools have deadlines of March or April-ish, you could submit your app like...the day before that deadline and say that you're going to take the OAT the following week, they'll wait if your grades are good enough. You can send them a fax of your unofficial OAT score report so they don't have to wait for your official report from prometrix.
However, if you're asking when is BEST to take the OAT, I would say as SOON as you are ready do. Don't wait until the last minute if you can help it.
