So when are these games played? Instead of 'friendlies'??
They are in the slots that the qualifiers for tournaments would be, between September and November with 2 matchdays per month spread over a 5-6 day period. After the group stage for the Nations League ends in November, the qualifiers for Euro 2020 begins in March 2019 with a double matchday, this process continues in June then September to November. The two competitions overlap in June 2019 when the 4 group winning teams from League A meet in a knockout format to decide the Nations League title while everyone else is playing Euro qualifiers