Depends on how far you stop down, and how much ambient light there is.
The EVF will brighten automatically. The kit lens is f/3.5 to f/5.6, and it's quite usable in fairly dim light. Of course I prefer to use faster lenses, and focusing wide open and stopping down is no big deal to me. In daylight it is pretty easy to focus at shooting aperture.
I'm using a modified Pen extension tube set as an adapter. When the lens is mounted, there is a tab on the extension tube that stops the lens down. A properly designed adapter for µ4/3 would not have the tab. Then, you could just press the button on the lens to stop down, prior to taking the photo.