Some of you may remember the 1900s when things moved a lot slower than they do today. Of course that is true of plants too.
People grow old and so do plants.
We gain experience and wisdom and trees mature to flower or fruit. Very often I think of all of the flowering trees I have planted and waited patiently for them to produce lovely flowers. My answer is six to eight years or more because the tree needs to grow and mature for flowering and fruiting. Patience is very important when you grow trees from seed. A lot of folks plant trees expecting them to survive without any attention but like small children they need a lot of care.