Hello aspirant I am here for helping you.
If you want to give Bank exam after your post graduation and then you want to go for CFA then don't bother about it because there is not any specific duration for which you need to apply in CFA exam but you need to have bachelor degree which is eligibility criteria for this as you are going through it after your post graduation so it's easy for you.
For going through private bank first you need to see that which post you are searching for then your degree  and score in examination with your knowledge will play a crucial role here.

I hope you got it.
Feel free to ask any query in comment section.
Best of luck.