The reason I start in small pots and move up is ~
The roots grow out to the sides of caontainer and then circle it, they do not fill up the middle of container, so they are wasting space and can be victims to the elements, like cold air on container or air running down inside pot to on soil that has been pulled away from side due to drying up (never in my garden, never dry).
This way they are circling a small container then going into a larger pot and the middle will have fat roots.