Age of domain make only confidential nothing any more. If any one will check it that you site is online from last three years then he can think once that you are providing services or selling products honestly and thats why you are stable till now.
I dont think age of domain can do any other thing for website.
The thing one should need to gain is more traffic to the site and thats the main thing one should notice out, i think it makes little impact but not so much.
I don't think that matters, but i think how you work that matters. Because surely if you will work prolific and mind boggling then age doesn't matter for you. But to maintain the business and quality is the most important factor.
Since the age of your domain is something you have no control over, it doesn't necessarily mean that your site isn't going to rank well in the Search Engine Results Pages (SERPs).