It's more advice but I'm making this post because I haven't seen a post on transplanting.
We all want to get that plant into a big pot with lots of root space so it can grow big and beautiful. Well this can ultimately stress a plant to death. Start small and work that baby up into a 6", 8", 10" pot
When you start your new plant from seed or cutting, you want to focus on the root system. That means you want those roots circling the bottom of the pot and up and down the side of the pot. I start mine in rooting trays then move it to a 3" or 4" pot, depending on how much roots and foliage I have. The more foliage the better, obviously, your plant can photosynthesize more than less foliage.
When you transplant, you tell your plant that it's time to focus on root growth. Your plant will want to establish itself again into new soil you have given to it. If you have just got it to sprout and put it into a 6"pot, it's going to stress your plant. It will be harder to set new growth. When your plant does establish itself it will start using those nutrients for beautiful foliage, blooms, and fruits!
When is it time to transplant? Your plant will tell you! The rootball is solid, water runs down the sides, dirt gets pushed up from its pot. Meaning, with only some roots moist, those inner roots are dry as can be and new growth is damaged, wilted. You'll see smaller leaves. So it's time to repot into nutrient rich soil.
When can we break the law? Well the only way is mocking or giving a plant perfect conditions to its native environment. If you have fresh oxygen, CO2, humidity then you may be able to get away with oversizing a pot but still, you're stressing your plant.
Some plants like large root space. Caapi is one, but the plant can still mature and use nutrients in the pot.
Cactus, I'm still a bit of a newbie on this one but cactus and succulents have a small root system. I've done cactus gardens and put them in shallow containers with no problems. Except for crown of thorns. They have quite the root system for a succulent. May need a little more advice on this one cactus and succulent experts on the forum.
I added a couple of pictures of common houseplants with a large root system.
A little jingle to remind you about transplanting,
too low won't grow, high will thrive!!