Summary for week 3:
Finally, after 2 and a half weeks, my second light (the first one was damaged) arrived!
Temperature was in a good range (min: 18.9°C, max: 29.1°C) and my fears of cold nights didn't come true. However, in terms of humidity, it does not look so good. When the lights are on, the minimum humidity is close to 36%, and adding a wet towel and a pot of water helped to keep it above 42%. When the lights were off, the humidity reached up to 82%.
My ladies had some huge growth spurts this week. The largest one is now approx. 25 cm tall and the other ones are at 20 cm. They can now all stand on their own, and the stems look really strong. They look a bit bushy, maybe I have to find out how to trim them or is this related to a low humidity?
They also started smelling. They grow up so fast :'). Let's see what the next week will bring! (Spoiler: timelapse video of the first 4 weeks :D )