A new comer in this field - How to start?
I would suggest you taking a Machine Learning and Statistics (Coursera, Udacity etc.) course straight away, since you have a profound experience in programming, so mastering any library wouldn't be of a big issue. Understanding of theoretical approaches is way more important than a particular library.

Main reason for that is the fact, that tutors of courses usually provide you with data big enough to understand the purpose of each algorithm/approach in the session/assignment so you will not only become proficient in some ML approach, but also understand which type of data can be then handled by a particular algorithm.

Also, I suggest you select a particular field of data science / machine learning, since data science, machine learning, statistics and so on, are just powerful tools and their application in computer vision, statistical modelling, natural language processing, fraud detection and other fields share something in common, but focusing on one field will allow you to progress faster.