I am sorry for the lack of pictures between germination and week 3, but my mobile died on me and I have not been able to recover the pictures.
Comments by strain:
Purplematic started well its vegetative stage, perhaps the strongest growth at early stages.
CBD 20:1 started weaker but after a week was recovering and aligning to the progress of Purplematic.
Pink Kush is one week behind. Initially I had germinated "Candy Caramel" from Autofiorenti.com. I tried 5 seeds, but all of them died as soon as the little root appeared. So, I changed strain after 1 week and moved to Pink Kush CDB from Autofiorenti.com. Conversely to its sister, Pink Kush germinated well and started strong its vegetative stage. Clearly the genetic of Candy Caramel was very week.