No comment about C# (wouldnt be my first choice) To build knowledge, cred, and potential customers: find an open source/side project that excites you to death,

No comment about C# (wouldnt be my first choice) To build knowledge, cred, and potential customers: find an open source/side project that excites you to death, use NewLanguage to do it, and then publish it on Github and relevant online communities. You may turn out not to like NewLanguage afterall. To slowly work new languages into existing projects: microservices have been a great way to sneak new technology into old systems. I've employed Erlang in PHP projects (autocomplete), Q in Node.js projects (websockets/in-memory tables), etc.