My shen SB80 is labeled 2006, i am the original owner.
It's been played quite a bit - so much practicing, orchestral playing, solo rep, and jazz. It has definitely opened up - but it's over 10 years old.
i had some work done by Jeff Bollbach, who sees a lot of these not long ago on this bass - he commented that it had opened up surprisingly well, and it was one of the oldest ply shens he'd seen. he seemed really happy that it was developing the way it was. When i mentioned how much i've played this bass, he made it clear that age in and of itself is separate from playing. So, age along plays a huge roll, and with my ply shen it was about 10 years when it sounded "seasoned."
I do also agree that they need to be played in - all acoustic instruments do - the first 100 hours of playing on a brand new well made violin are shocking how much the instrument develops. So, play it a lot, enjoy the bass, and let time do it's thing. don't put too much emphasis on trying to open up the bass - if your practicing the right things (scales and all that fun stuff) it will also vibrate the top in a good way to get it used to moving.