I would definitely advise to learn Python as the first or “entry” language. It not only has been implemented in Dynamo and Revit via PythonShell (shutout to Darren Thomas), but it actually has been implemented in Revit Macro Manager. Now, with that being said it is a .NET implementation called IronPython but limitations are very specific and it might be a little while before you notice any difference. Also, it’s worth mentioning that other design software, namely Rhino and Grasshopper, have Python implementation. In Grasshopper you can download ghPython and Rhino has a Python editor built into it. Now, people will most certainly argue that C is the native language for all these programs but from experience I can tell you that if you need a quick and dirty hack to get something to work and get it out the door, Python offers a more immediate return on investment in all these packages. Now, if you wish to do some more serious developments you will eventually gravitate to C and knowing Python will not hurt you one bit. Good luck!
Ps. There is a lot more material available here that references Python than any other language. You will most certainly get your Python related questions answered here (of course in context of Dynamo).
Hope this helps. Good luck!