Seedlingphase for me is to the moment they stand up as a plant with 2 cotyledon no leafs. When they have leaves and need the grow nutrients, id call it grow. You have small leaves, but i would always start on week 2. Soil is enriched with stuff to bring you through atleast a week normally adn they also dont need much. Flowering feed I would slowly switch when you adjusted light to 12/12 a week ago. First 12/12 weeks are growth, not flowering