The act of posting/uploading something on facebook when the majority of your friends are online. Your awesome post will appear in the newsfeeds of the many facebookers online at the time. This is done to recieve maximum likes, comments, etc,.
Prime Time Newsfeeding times include:
Anna: omg I came up with the best status for facebook.
Kelly: really? you should post it right now.
Anna: naw, I think I'll wait a little and post it around 8 o'clock.
Kelly: Prime Time Newsfeeding. Nice Work.