If all is well, we can start talking about the seasons 2020-2023.
Now, here are a couple talking points:
I believe that the best approach is to first add the top 16 UCL teams from the 3 seasons, because that's what people are most interested in playing (me included): Haaland in Man City, Cristiano Ronaldo in Man Utd, Messi - Neymar - Mbappe in PSG.
Given that we don't know when something can happen (broken hard drive, work, life, etc.) I think this has higher priority than adding the full 20-21 UCL first with Brugges, Ferencvaros and Istanbul Basaksehir, also because they will take more time in research, kits, balls, fonts, adboards, etc. (full 32 UCL is the approach
@ovide suggests).
So in my mind after we add the top 16x3, then we can add the eliminated 16x3 teams (the Marseilles, the Ajaxes, the Basaksehirs) and after that - the key NQ teams such as Arsenal 22-23.
I just think it would be a shame if we get bogged down for months/years with Midtjylland 20-21 and the likes, never reaching Mane in Bayern or Lewandowski in Barca.