How long a lack of practice does it usually take to forget the intricacies off the learnt Chinese? Particularly, intricacies of pronunciation.

I am just starting to learn the language, and what bothers me is that after finally managing to learn proper pronunciations of the language sounds, I may then forget it all if there comes a period of time when I’ll not be able to practice my skills. 

So, if anyone had a personal experience with this—how long of not practising did it take to forget what you have learnt and how easy was recovering the lost knowledge?
As a native English speaker, I've found that after leaving China for four years now, my ability to remember tones has been negatively affected. Second, is remembering words. Weirdly enough, having not read much these past years, I never really lost an reading comprehension (though as before I may forget the meaning of a word and/or its pronunciation). 

The best way to recover (other than returning to China and speaking with Chinese friends- obviously) is to watch/listen to movies and TV as this triggers those neglected neural connections, that you would be surprised to learn are quite resilient.