They'll take as long as they take, dependent on many variables. No sense trying to figure it out, assuming you've committed to growing to maturity from seed.

One way to get fruit sooner would be to graft mature budwood to the seedlings.

Or if you are really interested in discovering a new cultivar, graft some of the seedling budwood to a mature tree.

The fruit will be likely be less variable than something like an apple or a stone fruit that have been very extensively hybridized and grafted, so that's a plus.

Boy what a snarky reply! Fruits typically have some sort juvenile period before bearing- I was looking for an approximation. FYI, I do know poms aren't usually grafted- too many suckers. Thanks for the attitude.

I'm sorry, I didn't mean to come across that way.

lol I didn't see anything "snarky". You must be new to internet to interpret that as harsh. hah

yukkuri_kame really does make a point, I had mine in ground for 2+ years and still didn't get a single flower. Some people get fruit the following year after planting.
It just depends on way too many variables (weather, cultivar, soil, disease, insects, pruning etc.)

But generally I would say by year 3-4 you should get at least flowers if not fruit.

Ha! I had some pomegranates, started from cuttings of a neighbor's mature fruiting plant, that took 35 years to fruit - but...being an 8-yr old boy, when I planted them, I knew nothing of competition & juglone inhibition from the (then) young, but mature, black walnut tree, whose root zone they were well within.
Nearly 35 years later, when a new septic drain line was trenched between the poms and the BW - ultimately killing the BW - the poms began flowering and fruiting prolifically.
Was it inhibition by juglone, or just being shaded and outcompeted for soil nutrients by the larger BW? I don't know.

Thanks yukkuri_kame, it just sounded a little flippant to me- probably the usual lack of visual/vocal cues. That's sometimes a problem online.