I started nuting mine at 3 weeks with no nute burn. Actually, they have had root stimulator every watering since seedling, then on 3rd week 1/4 strength Grow Big,3.5 days later root stim and water only, then 3.5 days later 1/2 strength Grow Big, so basically every other watering until you reach full strength. I then waited a week and went to a Bloom nute, Tiger Bloom in this case,same way, 1/4 strength, I added my molasses in here, then 1/2 stength, you get the picture. I am now at full strength Tiger Bloom and going to switch to Beastie Bloomz next watering. They got molasses and root stim today. They are 49 days old, and budding profusely, with resin coatings looking yum yum. I wish I had a digi cam for some good pics...