What the best time to start conversation to get release from project

I am in project where we have to work project with langauge created only for that project with python, if I am luck then may be in 1-2 month minor task we get to work on python. I am in this project from last 2 years since I am not working on language or tool that accept by industry start loosing my skills. I am looking for release. switching company is not possible as most of them now start calling to office and I can't relocate due to personal reason. In my current place there is not much option.