You don’t have to enter a date or time, as System Restore will note the date and time at which the point is created.
If you’re here because of a blue screen of death, just wait for the “Choose an option” screen to appear after a few minutes. To access the Advanced Settings menu from the desktop, open Start, click the Power icon in the lower-left side, hold down ⇧ Shift while clicking Restart, and release ⇧ Shift when the Advanced Options screen appears.