Before you water turn the plant upside down and work the pot gently so the sides loosen from the plant and it can be removed. Keep in mind that you want to do as little root disturbance as possible. It is easy to cause transplant shock. At this point I personally like to sprinkle beneficials all over the roots.
Next set the plant into the container and again be very delicate. Now fill in all the sides with dirt but dont pack it in there. Water it and if the dirt sinks down too low simply fill more in untill it sufficiently covers the plant.
i use plantable pots and bunch them together in a clear container,i then put a airy soil mix under the pots and add myco fungi,this gives me great rots and i dont waste pots on plants
I say avoid transplanting & have a big pot to begin with. Somethng you can vegg & flower in. Just keep in mind that you need about a gallon per foot for a flowering plant.