What restrictions for google news feed?

Hello guys.
My site got approved in google news today.

I thought all time that my feed for news must be with only latest articles (published along 3 days now). But now I'm not sure, and can't find rule about, what posts should be in the feed.

Can you tell me please, should I export all articles to the feed, or I should leave is as it is, only published along 3 days?

I found it, I should add posts to feed only that were posted along 2 days