Hi@Shashi,
It depends on the performance. If somebody has practical knowledge and experience, it will become easier to get this kind of role. According to my knowledge, 2-3 years will be more than enough to get a senior-level role in the DevOps world. But it depends on the requirement of the company and other parameters.
If you do not have any prior experience, think about taking PG in DevOps before you begin the career path in this field.