Looking at those, you still have many weeks to go, they aren't even close to ready.
In my experience, even if a strain is billed as being purple, it doesn't mean it will go purple. I have had strains that had one phenotype that went purple, even though it wasn't supposed to. Sometimes they will go purple because of the environment, very often the cold will cause purpling. I wouldn't bank on that turning purple.
They look really good.