Trouble while installing MacOS Sierra via USB drive!

URGENT HELP REQUIRED!

Hello everyone!

I have an iMac (Mid 2011) I decided to do a clean install of macOS sierra! I followed all the necessary steps of

1. Downloading the OS package from the app store

2. Preparing the USB drive with disk utility.

3. Creating a bootable USB drive with Terminal.

4. Restarting and holding option key till when the boot options show up!

5. And booting from the USB drive which has the installer.

Os utilities show up, I opened disk utility and erased the primary hard drive (Macintosh HD) And then I clicked on install OS.....And I'm waiting since then for the installation screen. It doesn't show up!

Anyone knows what to do?