How to cast on at the beginning of a row

I have just reached this in a pattern, and I know I have seen it before, but I can’t for the life of me remember how to do it. Can anyone tell me how or point me toward a source for instructions?

Thanks!

Cast on at the end of the previous row, and count it as the beginning of this row.

Or… do a knitted or cable cast on at the beginning of the row.

sue