My great grandfather Søren Kristian Magnussen was born in 1890, and he got his fathers last name. His father, August Magnussen was born Magnusson in 1842 to a Magnus Andersson near Bullaren in Sweden (ignoring the mothers here only because they had no impact on the last names). August's brother Johan Alfred Magnusson had (at least) three children who were named Johansson / Johansdotter born between 1885-1890. So even that late some children's last names were still derived from their fathers first names.
It makes genealogy both easier and harder - on one hand apart from during and after the transition period you get the fathers first name "for free" (most of the time, except when they complicate things by using the name of a farm instead of a last name), on the other hand it makes searches for the transition period a real mess (as if the poor hand writing of everyone involved in record-keeping isn't bad enough).