Don't the actual answer, but would guess its sometime between year two and five. Have also noticed several oak seedling leaves are often retained far longer into the fall than typical and often exhibit more color than typical of their species. For example my Bur Oak seedlings at year two had red leaf color in the fall. Two of my current two year old Live Oaks have red leaves right now instead of dull green.

It seems that red fall color in oaks is something of a juvenile trait, that only a few species hang on to after the seedling stage - obvious examples being Q. alba, Q. coccinea, Q. shumardii, and some others.

It would be cool to find a sport of a live oak that retained that juvenile trait of red leaves in winter. An "evergreen" that holds RED leaves all winter instead of green. Then turns back green in spring with the new growth, staying that way until the next fall. THAT would be cool.

I'm not sure on color, but as for leaf shape, I have some burr oak,, Lyrata, Muelenburgi (missplelled) that look about the same now at a few yrs old. My Burr oak from Dax looks more like Burr than mine from Musser Forest, and the Dax one is younger.

Regarding the comments about oak leaves, I don't know when the start producing typical species leaves. But regarding the comment about a red leafed live oak, I noticed this tree on my daily commute. It has reddish leaves, much more so that the typical live oak, which you can see in the background. I can't find any other examples on the internet of a red leafed live oak, so maybe it's unique. It's not bright red, like a purple plum, but still redder than the typical live oak. I think it just turns green in summer, as I haven't noticed it until this winter.

Here's a close up of some sprouts on the trunk.