The orbital distribution of trans-Neptunian objects provides strong evidence for the radial migration of Neptune [1,2]. The outer planets' orbits are thought to have become unstable during the early stages [3] with Jupiter having scattering encounters with a Neptune-class planet [4]. As a consequence, Jupiter jumped inward by a fraction of an au, as required from inner solar system constraints [5,6], and obtained its current orbital eccentricity. The timing of these events is often linked to the lunar Late Heavy Bombardment that ended ∼700 Myr after the dispersal of the protosolar nebula (t 0 ) [7,8]. Here we show instead that planetary migration started shortly after t 0 . Such early migration is inferred from the survival of the Patroclus-Menoetius binary Jupiter Trojan [9]. The binary formed at t t 0 [10,11] within a massive planetesimal disk once located beyond Neptune [12,13]. The longer the binary stayed in the disk, the greater the likelihood that collisions would strip its components from one another. The simulations of its survival indicate that the disk had to have been dispersed by migrating planets within 100 Myr of t 0 . This constraint implies that the planetary migration is unrelated to the formation of the youngest lunar basins.Jupiter Trojans (JTs) are a population of small bodies with orbits near Jupiter [14].They hug two equilibrium points of the three-body problem, known as L 4 and L 5 , with semimajor axes a ≃ 5.2 au, eccentricities e < 0.15, and inclinations i < 40 • . Dynamical models suggest that JTs formed in the outer planetesimal disk between ∼20 au and 30 au and were implanted onto their present orbits after having a series of scattering encounters with the outer planets [12,13]. This resolves a long-standing conflict between the previous formation theories that implied i < 10 • and high orbital inclinations of JTs. The formation