I don't think having the Scoti in the northeast of what is now Scotland from 300 BC to 1 BC inclusive is right. I don't think the term appeared until ~300 AD, and it originally applied to people from Ireland: it only later came to be applied to the inhabitants of northern Britain when Irish became commonly spoken there (whether by immigration, conquest, or deliberate self-Gaelicisation under the influence of Irish missionaries).
More recently, the idea that the Picts conquered the Scots (which they'd done once before, in the eighth century) and adopted their language (something which they seem to have already started on) has gained ground.
