Yes and the "bantu" peoples had already begun migrating into what is now Limpopo and even KZN in the 3rd century. They were not newly arrived.
Of course some groups moved in at different times then others but different groups tended to assimilate together, so even if certain groups arrived after the 8th century they would have probably assilimated with decedents of earlier bantu migration.
Even Nguni groups like the Xhosa became the Xhosa because they assimilated with the indigenous non Bantu Khoi San, same goes for Setwswana speaking groups.
You are probably thinking about non Nguni groups like the Venda who can trace their lineage back to the kingdoms of Mapungupwe and Great Zimbabwe.
So the truth is that there is no single african or bantu group that arrived in South Africa at any one time, but to say that the Bantu speaking groups are newly arrived is false since their were plenty of pre-existing groups that arrived well before the 8th centruy.
Ah now that's a much better explanation of the situation, I concede my point then on that front.