Mass of the planet as a function of time. The mass of the core (red line) increases via pebble accretion until isolation mass is reached at 350 kyr. Then the envelope starts to contract (dashed lines), which in increases the total mass (solid lines). The contraction time of the envelope depends on the opacity of the envelope κ_env, where lower opacity results in a shorter contraction time, so that when M_c = M_env, rapid gas accretion can start. The planet is placed in a disc at t₀ = 2 Myr at r₀ = 10 AU.