An assembly for indicating a window milling progress and a casing exit trajectory in a well may include a cylindrical housing having an inclined plane that extends along a central axis thereof. The inclined plane may extend from a lower end to an upper end of the cylindrical housing. The assembly may include an indicating device. The indicating device may include a cylindrical body having a surface that faces in a downward direction. The indicating device may include a plurality of anchor slips located on a curved rectangular side of the cylindrical body. The indicating device may include a set of inserts located at predetermined locations along a length of the curved rectangular side of the cylindrical body. The assembly may include a coupling mechanism that connects the indicating device to the cylindrical housing.