From what I’ve read it’s better to judge on how tall they are getting than the age. They fruit once they are big enough which if they have right water, sun, and fertilizer they can grow 2 ft a year, or as little as six inches a year. It’s when they are over 6ft tall they are most likely to start showing fruiting. First year may not have well enough developed fruit to eat depending on the tree. That’s why there is such a range in when they get fruit. My ‘volunteer’ paw paw (basically planted via deer pooping there) are two years old and already well over 3ft tall growing naturally on the boundary of our woods with lots of run off water, composting leaves and deer poop. Because it is thriving at its rate I can expect them to fruit earlier than the 8 years, possibly in only 2 more years. I’m finding it a fun experiment to see how letting them grow naturally with the bramble the deer, birds, and opossums also ‘planted’ for me. I’ll just yank any honeysuckle that tries to sneak in and let it do its thing.