Sorry for the luck, I hate it when things like that happen. I wish all companies would put a mix on date and/or best if used by date. I guess some don't due to not really knowing an exp. date, however they could put a 1-2 yr. span with best by.
Next time you go to order, see if the brand you want has their own website (if not ordering from a maker). If they do look to see if they include dates, if no info is given, shoot them an email and ask. It might take a few days for a response, but that's better than having to wait on something that may never arrive.