1. Strings: The strings, which include the violins, violas, cellos, and double basses, are usually the first section to enter in an orchestral piece. They often provide a foundation and melodic support for the other instruments.
2. Woodwinds: The woodwinds, which include instruments like the flute, oboe, clarinet, and bassoon, typically join the Orchestra after the strings. They often play melodies, countermelodies, and accompaniments.
3. Brass: The brass section, which includes instruments like the trumpet, trombone, and tuba, usually enters later than the strings and woodwinds. They often add dramatic and powerful elements to the music.
4. Percussion: The percussion section, which includes instruments like drums, cymbals, and xylophones, can enter at various points in the music, depending on the desired effect. They often add rhythmic drive, accents, and color to the Orchestra.
5. Keyboard Instruments: Instruments like the piano, harpsichord, or synthesizer may be added to the Orchestra at specific moments to provide harmonic accompaniment or special effects.
6. Other Instruments: In larger orchestral works, additional instruments such as the harp, English horn, or bass clarinet may be included and join at specific points in the music.
It's important to note that the exact instrumentation and timing of instrumental entries can vary greatly depending on the composition and stylistic preferences of the composer or conductor.