My iPhone 4 has been updating to the iOS 7 for the past hour?

I'm at my sisters, using her Wi-Fi. I'm ready to go home, once it reaches the black screen with the apple logo, can I disconnect from her Wi-Fi &' it complete without error?

I wouldn't try it. Everyone in my house had problems updating. I wouldn't take the chance to have to redo it when you get home

I would not.
i just upgraded my ipad. 2 hours on Wi-Fi to download.
maybe their servers are slammed.