Honestly don't know the answer on this one because I haven't been in this situation before. With that said here is what my private equity partner with much more experience than I told me.
If the effective date of the split for shareholders of record was 9/3 then every share in circulation as of that date is subject to the split. So if people sold those shares after 9/3 they would still trade at the old price (i.e. ~0.0005/share) and be subject to the split until they were exchanged for the new post split shares according to the terms of the R/S memorandum. The only shares that you could buy after 9/3 and before the effective date of the split, ~10/20, excepted from the split are newly issued shares from the company issued AFTER 9/3 which would carry at least temperarily a different trading symbol on the exchanges.
There are many more details but my brain shut down before I could digest them all. Hope that helps...