I send prints the day or if its too late, the day after recieving payment. I make sure to have at least the amount of prints on hand as I am auctioning. My current problem is getting people to pay on time - I've got one customer that bought a print on feb 15th that still hasn't paid. But I've got a few good customers since then, paying the same day, or the day after committing to purchase. I'm always so happy that someone likes my work that I even upgrade them to airmail at my cost; I'm not too great of a businessman...
I think you should ask for your money back and probably buy a print from me