This is correct you can only set release/expiry dates for catalog within import but not for products which will need to be manually applied at this stage.
This is pretty crazy you can't import products and set a release date!! And this is still an issue 4 years later. This is beyond a standard feature to be able to sort products by newest to oldest and most clients with more than a few products use excel imports to manage products. Even if the import didn't have release date but at least imported products with the current date and not January 2000 that would be somewhat helpful and then if products that already exist get imported that the release date does not get updated that would be nice.
I did think of a workaround though for anyone else searching for a solution to this. If you're using module_data to output products you can import the date in the weighting/order field or a custom field like "20161130" and then use the "order" parameter with module_data to sort by weight which would sort it by date.