In Batman's first appearance in Detective Comics No. 27, he is referred to as "The Bat(-)Man" exclusively.
In the issue, characters say "It's the Bat-Man" rather than "It's Batman". For example:
It's the Bat-Man — get him!
In which issue does a character refer to him as just "Batman" for the first time? In particular, when is "It's Batman" (with no definite article) used for the first time?
For the purpose of this question, hyphenation ("Bat-Man" vs. "Batman") is unimportant.