I would also say Twitter or here because if you use the websites that claim to be up to date in most cases they are not.
(....)
Yeah, Twitter is good BUT you should consider who is your following people, so if your following on Twitter is not interested in such upcoming cryptos, it is limited what you can see.
Since we are already here in Bitcointalk, I can suggest is another section in Altcoin which is
Announcements (Altcoins) .
Some of the altcoins announcements are also starting here.