Well I've been in contact with Codemasters over the past couple of days about AL trying to get an interview with them (not quite yet) and they will not state specifically when the beta will be out on FP. I guess we will just have to wait. If I get new info, I'll post it though.
But I'd also gather the latest we'd have to wait is indeed the 24th since Pre-Orders will get access then.
In the AL forums they said Aug 24 is a projected date. Not an exact date for Pre-Orders to start beta.