In those days, full mourning, usually black or dark purple was for 6-12 months. Depending on the closeness of the dead person to the one wearing the mourning clothes. Half mourning was another 3-6 months with a change to lighter colours. Depending on the court, of course. It is much more simplified, if followed at all nowadays. Some people were exempt from mourning- pregnant ladies and children, young people. Men got away with just the black armband.
There is or was an excellent discussion about this on the forum somewhere, but I could not find it.