No, creating a thread four days in advance would qualify as being early. In the case of the Mercedes thread, there was actual content to discuss because of the teaser image and now the render. But if someone created a thread right now and said "This car launches in four days. Discuss.", then that would qualify as being too early. The C30 will launch in roughly 12 hours.
Anyway, Sauber have actually picked up some sponsors for this year! Mad Croc Energy have renewed their deal to sponsor the team and may have some more prominent branding, whilst Mexican tequila brand José Cuervo - one of the best-selling tequila brands in the world - will feature on the sidepods and nose of the car. There's no word on what, if any, branding Telmex will have, but given that Carlos Slim bought into the team and both Peréz and Esteban Gutiérrez are a part of the Telmex driver program, I'd be very surprised if the company's logo didn't appear on the car. Plus, Telmex's colours are light blue, which will make the car fairly distinctive.