The target is to release the official Qt 5.8.0 release during January 2017 so please try the RC now. All feedback is welcome! Please report new bugs to bugreports.qt.io. You can also send e-mail to Qt Project mailing lists or contact us via IRC.
You can update Qt 5.8.0 RC in your existing online installation by using the maintenance tool. You can also download new installers (online or offline) from the Qt Account (for commercial users) or from download.qt.io.