Installing Mojave on my MacBook Air

Installing Mojave on my MacBook Air

I downloaded and I’m installing Mojave. I assume the update checks compatibility before it starts. I did have one question to close all apps which I did and it began the process. Now I have a dark screen no progress bar,the lights on the keyboard are on, and I have no idea if anything is happening. It’s about four hours now. How much longer should I let this go before trying to decide if something went wrong?