How do I locate the date a submission is made public?

Publication date(pdate) means when the venue marked the paper as accepted.

Modification date(mdate) means when the last time the paper was modified.

The odate means when the submission becomes public. To check the odate of a submission, see the note object https://api2.openreview.net/notes?id=

To find the id you can check the url of the submission, for example https://openreview.net/forum?id=KS8mIvetg2 . Use id=KS8mIvetg2 , the note object url will be https://api2.openreview.net/notes?id=KS8mIvetg2.