It all depended on how close we were to certain people. With our girls, we didn't tell anyone we were trying, because it only took a month both times. We did tell people we were pregnant right away with our oldest though, because we found out on Mother's Day, and we were calling everyone any way.
With #3, our friends eventually knew we were trying because it took quite a bit longer, and there were a lot of ups and downs with the process. We waited longer to tell family once I was pregnant though, because we knew they wouldn't approve. Complicated, sad, but true.