Yes... keep the cards/signs, just change the date. It would be be great if you wanted to continue taking photos. Here are some detail description of the steps
that I wrote up for Lysa Morgan
for doing wdydwyd at an event. But, you could do it in all sorts of ways. I plan to do a series of books on wdydwyd around different groups/communities, and I hope to include a bunch of Collaborating Artists' work... so keep doing them, especially if the process stays interesting for ya, and if the art you produce is still interesting to you.