Same. I’m sticking to English as much as I can when talking with my son. Lately I found him trying to speak Japanese with me and I replied gently back to him saying sorry I don’t understand. He seemed to understand as he very quickly switched to English.
My son can’t speak full sentences yet, only singular words in both English and Japanese. I don’t think he knows he is speaking two languages.
It’s going to be a long journey on this I feel.