(1) Poster Session: Posters are assigned by day. You can check your presentation date on your contribution page or via the poster session page, which lists all posters.
https://indico.cern.ch/event/1471803/sessions/624979/

The board ID will be added to Indico by the weekend before CHEP. This can also be checked from your contribution page. The ID will follow the format: XYY-Day
where:
+ X = Row
+ YY = Order of the poster
+ Day = Presentation day

For example: https://indico.cern.ch/event/1471803/contributions/7085180/
Board: 436-Tu = Row 4, Poster 36, presented on Tuesday.

(2)