You can change delay time using preset that series to capacitor
When push the button capacitor drop high current and that capacitor connected to base voltage 0.7v drop. When it drop and it allows to flow current another transistor across 47k resistor then led start to on until reach capacitor charging voltage upto 0.7v when it reach than capacitor connected to transistor on and it drow high current throw 47k resistor that current will limit to led connected transistor on and it is going to off
