Hello Sarthak,

Yes you can give your intermediate exams after 3 years that is after completing your graduation.

As you have to register yourself for intermediate exams atleast 9 months prior before you are going to give your intermediate exams. But personally if you are giving now foundation exams and are  waiting  for 3 years for  giving your inter exams then you are not doing right as you can on completing your graduation u can directly get admitted to the intermediate level through direct entry route. So there is no point of giving now your foundation exams and waiting for 3years. But if u want to do so then you can go for it there is nothing wrong in this.

Hope it helps.

Good Luck!