Well, once again, according to the U.S. Copyright Office, it appears that BA12 is the winner by a week:
Type of Work: Serial
Title: The Batman Adventures.
Serial Publication Year: 1993
Description: print material.
Frequency: Monthly.
Publication History: [No.] 1, Oct. 1992-
Copyright Claimant: DC Comics, Inc.
Issues Registered: no. 5, Feb93. Created 1992; Pub. 1993-01-05; Reg. 1993-02-17; TX0003486207
no. 6, Mar93. Created 1993; Pub. 1993-02-02; Reg. 1993-02-17; TX0003483195
no. 7, Apr93. Created 1993; Pub. 1993-03-02; Reg. 1993-04-22; TX0003532246
no. 8, May93. Created 1993; Pub. 1993-04-06; Reg. 1993-04-22; TX0003531853
no. 9, Jun93. Created 1993; Pub. 1993-05-11; Reg. 1993-05-18; TX0003545466
no. 10, Jul93. Created 1993; Pub. 1993-06-01; Reg. 1993-06-21; TX0003576687
no. 11, Aug93. Created 1993; Pub. 1993-07-06; Reg. 1993-08-04; TX0003597968
no. 12, Sep93. Created 1993; Pub. 1993-08-03; Reg. 1993-10-27; TX0003661101
no. 13, Oct93. Created 1993; Pub. 1993-09-07; Reg. 1993-10-27; TX0003662680
no. 14, Nov93. Created 1993; Pub. 1993-10-05; Reg. 1993-11-12; TX0003675201
no. 15, Dec93. Created 1993; Pub. 1993-11-02; Reg. 1994-01-24; TX0003726425
no. 16, Jan94. Created 1993; Pub. 1993-12-07; Reg. 1994-01-27; TX0003740611
no. Feb94, special. Created 1993; Pub. 1993-12-14; Reg. 1994-01-24; TX0003726427
Basis of Claim: New matter: additions.
Names: DC Comics, Inc.