Hey. Sorry for the long response.
Your mix is what we call "Hot Soil" (very nutrient-rich soil). Fox Farm Ocean Forest and worm compost are already very rich in nutrients. By adding Gaia Green Bloom and a universal fertilizer right from the start, you’re taking a big risk of nutrient burn on young plants.
My suggestions:
Universal fertilizer: I recommend dropping it. Gaia Green is an organic slow-release amendment that pairs very well with worm compost. Adding a universal fertilizer (often synthetic) risks throwing off the pH and saturating the medium with salts.
Mycorrhizae: This is an excellent idea, even essential with organic amendments like Gaia Green. Mycorrhizal fungi will help break down nutrients to make them available for the roots. Apply them directly to the root ball during repotting.
Silica: A very good addition as well. It will strengthen the cell walls, making your stems sturdier to support the weight of the flowers and helping the plant manage heat better.
Note: Always add silica first to your pH-adjusted water before any other product. My advice:
Your mix already contains a lot of nutrients. If you’re using Gaia Green Bloom (2-8-4), save it for mid/late growth or the beginning of flowering (top-dressing). For starting out, Pro-Mix HP and Ocean Forest will be more than enough for the first 3-4 weeks. I hope I could help you. Have a great day!