Thanks for the feedback. I've added a request to our backlog to address this issue; we'd likely use the date when the add command is run. I don't have a timeframe for when this work will be scheduled.
In the meantime, if your package's Description file includes a Date field already then RSPM will respect that value.
Also good to know, if you use RSPM's Git building feature to publish packages from a Git repo, RSPM will automatically add a Date field to match the commit timestamp for the commits being published to the repository.
I think it could be something to add when I build the package just before publishing it. An option in devtools::build can come handy for that if not already present.
https://github.com/r-lib/devtools/issues/1327 might be of interest, though I think its for install not build. CRAN does the work of adding this field which is why it'd make sense for RSPM to do so as well.
Just chiming in to say that our internal release tool for R packages adds a Date/Publication field to the DESCRIPTION file in the same format CRAN uses, which seems to show up correctly in RSPM even for non-CRAN packages.
If you have a similar tool or process in place, it's a nice feature to add.