I started giving nutes at day 20, yesterday. The grow mix I'm using is moderately pre-fertilized, it says on the bag it should be enough for the first 3 weeks. It has worked out pretty well in the past. But you're right it does look a bit pale. I was just concerned that it might be lock-out due to incorrect pH and I figured adding nutes then would be bad. It has bounced back for the most part but it's still a bit pale looking.