I have 2 children in Japanese schools. 4 and 7 currently but my older one entered school just before 6. I had to beg the preschool principal to let us in because he said my son was too old to learn Japanese.
Either way, my daughter is 8 months in and my son is at least 1 full school year in (pre school and finishing his second semester of first grade). Neither are fluent. Neither are fully grasping what’s going on at school without some english help (usually the teacher doing their best).
While they have had great strides (my son is first in his class on hiragana/katakana/kanji), they are not even conversational with other students. I know they will get there. I want to post this to show that even “sponges” take a long time to acquire the language. Keep going guys, you can do it!