You can see a figure from ministry of education here (first figure - it shows the age of the starting student): https://www.dst.dk/pukora/epub/Nyt/2005/NR242.pdf
The title of the chart is translated into "Average age of new students", where the top part addresses bachelors-students from each of the 5 mayor areas (technical, societal etc), while the bottom part of the graph shows the vocational education system here.
After they start, they will use 5 years minimum to get their degrees. Bachelors are worthless in Denmark.
EDIT: I know the first article is from 2004. Here's a 2016 article that states that new students at the University of Copenhagen (largest in Denmark) had an avg. age of 22,7 in 2016, which was a year younger than the avg. age in 2015: https://uniavisen.dk/alderspraesidenter-eller-groenskollinge...