There is no age bar for IELTS. There are some test centres in India where you can give the IELTS exam. Since you are planning to pursue higher studies in Australia, you should go for IELTS academic. If you don't know English pretty well, it would be hard for you to clear IELTS. If that is the case then you may take some coaching classes which prepare for IELTS and TOEFL. Also you should give a lot of practice tests available in the internet so that you can get an idea of the actual exam pattern.

Hi...

You can give IELTS any time there is no bound in age limit.