I have a cople of Mimosa Pudicas I have been growing in three inch pots for about three months since germination.
The leaves on one started yellowing; and since I knew the lighting condition and water were o.k., I felt that maybe they were root bind.
Boy was I right!
I know the roots don't like to be disturbed; so I shook the whole ball out of pot and set whole thing in a 6 inch pot.
Roots were going round and round and protruding outta the bottom of pot. I would have never believed the root system grew that fast in these plants.
I will definately repot after say, the first month?
I just got some seeds for Desmodium Gyrans or 'Telegraph Plant' and can't wait to start them.