how lond does it take for a replacement iphone 6 under warranty by service provider

I just purchased an iphone 6 16gb, and in less then a week plus the phone has completely came to a standstill position (Hangs). When I tried to shut down, that's when it completely hanged while you still the processor still running and you can feel the heat.

And during that week its, I used to have ones or more where it hangs when switching from apps to the apps (Ex. photos to msg )

Note, I haven't downloaded any apps yet .