If what you mean to say is "in our day" (singular) that is something you might hear people say. For example my grandparents might say to me "Back in our/my day we didn't have cell phones and we had to walk to school every morning even during a blizzard." When people say "back in my day" they're saying "when I was growing up" or "when I was younger" and then they proceed to talk about that time in their life.

It means currently or at present. It is used to discuss the present. Example: Nowadays all children in New York City have access to kindergarten.