How long does it take for a Maine Coon (half breed) to physically mature?

My cat Maxi I believe he's part Maine coon and I want to now how much longer it'll take for him to mature. He's almost two years old now. And on breeders sites they said 3-4 years. But they didn't explain if it was a male or female... So I'm wondering if any one who can give me a good answer on how long/big and how many more months or years I have to wait before he stops growing.