The difference in what you, kyle and juices are doing now... and then... is number of players in the list. The divisions are distributions... fewer players in the list, mean fewer players in each division.
I've seen several folks say it's all about wins/losses now and ratings don't matter... I'm not sure where they pull that from, but from what I understand your daily ratings are what place you in a division. You are still compared to whom you are playing. If it were all about wins/losses then going undefeated would have you in Onyx - that's doesn't necessarily happen.
I don't think it takes any longer for trueskill to "work" in Arena. Rate poorly against bad kids and win (relative to others in the game)... and it will take longer to reach Onyx for sure. Rate highly and you should be seeing Onyx folks on your last day of rating. That scenario has been true for me every season I've played Arena... even this one. Kyle and I went in with just use two recently. It was my fifth day of ratings... and as expected, we matched against kids who were Onyx after our first game and got dumped on because we had a couple silver guys. Typically, I see Iron on the first, Bronze second, Silver third, Gold fourth, and Onyx fifth - depending on number of games and where my daily ratings ended the previous day. Both seasons I played I qualified in single digits in Onyx but as others, the number slid from lack of play.
If you want to hit Onyx quickly, it's almost better to go in without 4 heavy hitters so that you rank first or second every game on your team and maximize your ratings.