We should make custom Sylestis auto-adults. Nothing is more annoying than having to wait a week even with pies, to age to adults. At least for Mystical Essences

I like the wait, it gives you tension to stay on the site more :)

We should at least shorten it, though. Also, keep in mind, this is only for generated Sylestis, probably only ones made with Mystical essences at that.

Nah I like it.

I don't think it's necessary. Generated sylesti's starting out as adults would be far too advantageous. As for shortening the amount of time, we have magical pie's specifically for that. Two magical pies will cut the time down to a 6 day wait.

I've seen stuff in other games that are the equivalent of this suggestion, and they work out well. Not sure how that would translate to here but I can't see a huge reason why not to have it on the most expensive essence only.

A long time ago, there were only two essences: regular and enhanced.
Enhanced, in other-site-terms, was the only equivalent to making what you call a "custom" pet.
Enhanced essences were 1000 diamonds back then, but could also be gotten from other areas such as nurturing and drops.

But because enhanced essences had a color swing that made it seemingly NOT worth 1000 diamonds (among other reasons. such as the ability to drop from other areas of the game), Mystical Essences were added and were the new 1000-diamond essence, while enhanced essences dropped to 750.
The only difference between mystical essences and enhanced essences is: a) colors on mythical essences are more accurate, and b) mythical essences do not drop anywhere else (except contest prizes).
Thus, project makers bought the 1000 diamond essence FOR THE SOLE PURPOSE of being color-accurate.

From now til then, the standard of buying "customs" was just to make your project as color-accurate as possible.
Aging is a constant across this entire game.
Your newly-made pet still can do things like level up, battle, go on missions, and so on. It's not like breeding was the ONLY thing it was meant to do, as this game is all about (oh all the different things you can do with a pet).

So...

I can see why custom-makers feel entitled when they come from other games that promote buying their cash currency to go straight into the breeding mechanism. Many virtual pet games go big on their breeding mechanism, so there isn't such thing as a "wait" when you pay into breeding.

I totally would think this suggestion would be cool if it was like a 1200-1500 diamond essence (oh hey you paid 200-500 diamonds extra for taking away the aging process compared to buying some pies!).

My two cents.