Going from leaked benchmarks & precedent of last generation(s) it seems like the 3000G(H/U/ect) series is the 12nm Zen+ refresh of the 2000G parts(Which were 14nm Zen1 parts but that launched shortly before Zen+ parts, which were exclusively non-G 2000 series, so there were no 1000G series parts but that's kinda what they were). Then the 3000 non-G parts will likely follow a few months later with 7nm Zen2. 7nm APU's will almost certainly use Navi rather than Vega, so we shouldn't really expect them before Navi's discrete launch(Which is expected much later in 2019 than Zen2 I think), and will presumably be 4000G parts, about 12 months after these 3000G parts launch would seem a sensible guess(And it might not be the only set of APU designs they're launching around that timeframe going from console rumours).