I have a scene where Arden, immediately after returning home, speaks in his native language and cringes when he hears his thick foreign accent. My question is, assuming he's determined to lose it, how long would it take him to relearn his original accent in his L1? He most definitely wants to regain his original accent and "talk proper", as his L2 is a reminder of a dark period in his life and also marks him as a stranger in his own country.
What would be a reasonable timeframe? Three weeks? Six months? Longer?
I did a number of web searchs, but the situation my character is in is a bit different than the norm for dual culture/second culture kids -- which would be probably the closest real-world equivalent -- as he spent several years seperated from his native culture AND his family and other native speakers of his first language. Arden had no one to reinforce his original accent and over time the phonology of his L2 became more prominent.