Big data is a so big world. Not trying to discourage you but I don't think it's a good idea unless you can do Java/Python/Scala/Pig/Unix coding and scripting. It's a cloud computing and quite a different world then RDBMS. Hadoop world is keep on updating with new features and component. Storm, Kafka, Spark, cassandra are some hot trend on big data nowadays.
Learning hadoop is not as simple as other technologies.
You asking 2-3 years of experience? How you gonna show your experience to consultancy? Most of consultancies don't care about your years of experience. All it matters is your contribution to the consultancy. If you are working long enough to any consultancy and accordingly you will have raise. Most of consultancies have terms and contract. Longer you work for them higher the rate you will get.