WARNING on the Yashica shutter: DO NOT try the self-timer. this is the red-dotted lever at the bottom of the lens. Just avoid it for now. two reasons:
One, the shutter will be seriously jammed if you activate the self-timer when the flash sync (middle right yellow dot lever) is set to M. There is a physical mechanism designed to prevent you from doing this, but it doesn't take much to over-ride it. Again, DO NOT USE the self-timer if flash is set to M.
And knocking that little lever to M is not difficult!
Two, the self-timer is often dirty and dragging. Although you can often just push the lever until it winds down and releases finally if it does drag, just don't chance it for now.