Timeline for Bunzo and PJ

Adding a spoiler tag just in case. Upon a revisit to chapter 2 something struck me as kind of odd. We know the game station was used to test the orphans for the bigger bodies initiative, however… Bunzo and PJ are both mascots for the game station and are also bigger bodies, and it’s clear they’ve been a part of it for a while, their names are in the recording explaining the rules of their respective games. So my question is, just how long have PJ and Bunzo been around for? Were they the first bigger bodies? This would mean that they had to have been created before the experiments really even started. Am I missing something or is this a valid question? I’m not quite through chapter 4 yet, so please politely tell me if I missed something