No you cannot pick it up same day. You must wait till next day or it will not be available.
Technically, yes you can. But ideally, No its not possible. Since THIS post office closes at 4pm and the clerks are gone, there won't be anyone to assist you. And most Mailman come back to the office after 4pm. Best to wait for the next business day to avoid wasting your time to the post office.
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