This doesn't necessarily imply he has been active for only a month. It may imply that his appearances have increased significantly in the past month. Batman may have been active already for a year or more, perhaps appearing only once every few months or so. As Bruce has grown more experienced in the Batman role, he is likely going out on patrols and missions as Batman more frequently.
Reply by DanDare
on February 25, 2017 at 9:38 PM
Maybe he was hiding in a cave before that.
Reply by DarkZero
on February 2, 2018 at 9:16 PM
This doesn't necessarily imply he has been active for only a month. It may imply that his appearances have increased significantly in the past month. Batman may have been active already for a year or more, perhaps appearing only once every few months or so. As Bruce has grown more experienced in the Batman role, he is likely going out on patrols and missions as Batman more frequently.
Reply by A-Dubya
on March 15, 2018 at 1:56 AM
Yeah, it's just that the public hadn't seen him much, hence the wild myths. "I hear he drinks blood, I hear he can't be killed" etc.
Reply by tmdb53400018
on March 15, 2018 at 1:59 PM
The Batcave, of course.