Hey.

Many Law graduated opt to take the Civil Services exam after completion of their law degree. Many start preparing during the degree and many take 1 or 2 years after the degree for preparing. You can start sorting the subjects that you can opt for. You can also choose law as your subject. Decide the time you want to give for your preparation and start preparing for it. You can attempt the one being held  in June too for experience as you will be done with your degree till then.

You can use the link below for more details.

https://competition.careers360.com/exams/civil-services-examination

Best of luck