You'll want to check with a host to see when they come out next and be there waiting for them. The hosts will cut the line for each set, so you won't wait more than 30-45 minutes no matter what. It's not nucking futs like it is at WDW.
And they are out every day from September 12 - end of the Christmas (Jan 3 or 4 or something).
Also, on some days Jack might be out all but continuously (if you get my drift) but Sally will still alternate on/off.