most cats I think start to calm to calm down when reaching the 10 month mark. Altho like many others have said they still have their crazy sprees. Pebbles is the most miserable cat ever who doesnt play. She is 14 years old, she still has her nutter sprees where she runs around the house like a maniac, the kittens look at her in shock because she is the miserble grumpy one!
The others still have their moments when they be nutters, they are 11 months old now. In the last couple of months they have definatly clamed down A LOT