LLM is 1/2 Year programme & each universities has different criteria for the LLM course duration. There is an entrance exam for the same.. There is no any certain period for Practice as it all depends on your capability, You can do the practise till the time you are not confident to be the lawyer. You will be required to clear an entrance exam named AIBE and then you shall get the liscense. You can give this exam after graduation in LLB as well.

Good Luck!