Actually, I am thinking of applying at several top in the USA.

What do you think about an early application? I could send my application by June 2008. However, the deadline runs in most cases until December 2008 or even later. Could it be seen as negative if I would send my application so early?

It would be very helpful if you could help me with this.

Wait until they start application sessions/open their on-line application services, post new materials and etc.
Before this you won't just be able to conveniently apply for instance to NYU, CLS, Penn and other schools on-line.

After all, you won't benefit from such an early application, everyone has equal chances (at least they say this), save the school itself has an official early application (example CLS).

Just gather your materials, think million times of your PS content, and send just as they are ready to accept it.

Good luck.

Many thanks for you answer!