Crowds at Vallée des Joux and Dent de Vaulion

Hi, I don’t know Switzerland at all and was wondering if Vallée des Joux and especially Dent de Vaulion are packed early in the morning or late in the afternoon in July and September? If so, do you have any quieter spots to recommend in the area, or in Luxembourg (yes, I know it’s not the same country 😉)? Thanks a lot!