How many hours did it take for the approach to work?

I committed to this for 6 months. Also I studied around the same time every day. What also helped me was that on the course of the day I would force myself to count in Japanese and to try to think in Japanese. Sometimes I would be so distracted that I would catch myself actually thinking in Japanese for a good amount of time.

How far would you say you got at the end of 6 months? I took a Japanese 101 class a couple years ago and still remember some basic phrases/verbs/etc and how to read katakana and hiragana as well as probably 50 or so kanji. Been thinking about getting back into it so that I can at least use it at some semi-basic conversational level for my trip.

I would say that I got to the point that I was able to understand the majority of the words on Japanese songs and movies. The reading part on the other hand was another story. Talking I was at a elementary level. I was able to defend myself somewhat.