I need an authoritative source that provides the publication date of Distiller 23.0 please

You need first to determine the subversion (23.3.20284.0), as there may be prior versions, even beta versions available. There was probably 23.0, 23.1, 23.2 and then the current version 23.3 available.

The signing time of an executable is when someone at Adobe decided that it is time to sign that version. The OS uses the signature to determine if the executable comes from Adobe and has not been modified. So that is the very first time that the executable can be released to the public. Any unsigned executable would raise an alarm during installation. So only signed executables are running on a machine.

The digital signature is a formal proof of something. That should be accepted by tribunals as of my layman's approach. It's like signing a contract. You put in a date and a signature, and it is considered to be signed at the date indicated.

You can also ask Adobe formally for the release dates for each version and subversion, including the public betas, if there were. You should do that in written to the Adobe headquarters (address on the website). This forum will not produce any “authoritative” answer to your request.