While we always use the F. dining package, as the PP said, it IS a slower week (usually). I would watch the line carefully, though. Check and see what it looks like at 11/2 hrs before show time. If it looks like the line is building, you may have to get in line then. If you are there on an EMH night, then expect heavy crowds and a long line.
You just never know- it's a roll of the dice. Some say they get in only half an hour early, others find the amphitheatre SRO with an hour yet to go. Hence our preference for the dining package.