What a great problem to have! I’m so glad to hear that your succulents are thriving so well.
Now that you’ll be moving your plants to larger planters, I still highly suggest keeping your soil mixture to the larger particle size. Bonsai Jack soil is premade and designed especially for succulents, but if you’re eager to learn for yourself, this basic recipe is easy to follow:
1 Part Pine Bark Fines
1 Part Turface (an absorptive rock)
1 Part Crushed Granite
Coconut coir and DE are great, especially when you don’t want to worry about your watering schedule. I’d recommend following this recipe:
1 Part Coconut Coir
1 Part Pumice
The important thing to remember with soil, whether planting for the first time or repotting, is to make sure that the soil has a large particle size (1/4” or 6mm ideally).