It's looking like right at 4 weeks old. I'm worried about the burn you have on some of your lower leaves. I see that you're just watering with plain water so it wouldn't be a nutrient related burn as it appears at first. Have you fed this with nutrients at all yet? The more likely cause based on it being fed with plain water is a magnesium deficiency. I'd recommend adding half strength calmag plus to your feedings and see how it does. This should clear up the issue you're having now. Due to the size of the plant it will need a good feed soon or you will likely see many more deficiencies spring up. Hope this helps!