The only people who determine the actual date are Tesla and their accountants. Until they announce a date, everyone else is just guessing.
Generally, companies will announce as early as they can. There are two reasons for this. It instills confidence in the marketplace that they know what they're doing and are in control of everything. And it allows less time for any leaks to develop. As Tesla matures, I expect their quarterly announcements to creep earlier.
Elon seems to know a lot about timing events, and if the results are good(*), I expect he will make sure they come out before the options expiry on August 17. I doubt they can be hurried as much as July, though, the company is still doing new things like shipping overseas. Anyway, time will tell.
(*) I think consensus here on TMC is that we expect the results to be good, at least in the sense they will revise forecasts up some more, and maybe beat Wall St estimates of revenue, margin and deliveries.