So.. How exactly does pet growth work?
See I still have my first generated pet at the "Adolescent" stage, whilst the other pet I got in the beginning is now an "Adult". So is that a glitch? Or do generated pets just take longer to grow?
And if it's the latter how long do I have to wait for my pet to grow up?

We did a breakdown of pet maturities required for them to age here, but basically, all generated sylesti (including starters) start at exactly 216 maturity hours* (so it's like they just reached adolescence from being a hatchling).

Meanwhile, wild-caught sylesti can have any maturity hour over 216, and thus be new-adolescent or adult or anywhere in-between.

(*maturity hours start at 0 in a newly created eggling, and cap at 648, which is adult. If a pet's been genetically tested, you can see this number, but you can't see it in untested pets or any generated pet (because you can't test them))

Oh I see! Thank you very much for giving me an answer to this! :D