For the Wall Street Challenge, you need to trade for at least 2 days, but there is no rush to finish if you need more days to reach your Profit Objective. So, you must trade for 2 days minimum, even if you hit your Profit Objective before then.
If you manage to make a 10% profit in your account within 2 days and follow all the rules, then you’ll qualify for a Prop Funded BX account.