Question
Once the Mimosa wood is split, when can it start to be burned? Right away, after a couple of months or next year?

Answer
Mimosa wood burns clean and will have no problems with sparking and residue buildup. It is a fairly light wood and will be consumed faster then say oak or hickory. It does not have the resin in the wood like pine so it will not have the "popping" properties that pine has. No problem in the fire place. I would let it dry and it should be great next winter.

It will burn best next year--right now it would be too green unless it came from a dead tree. Green wood tends to create creosote so it is best to burn dry wood.