It doesn't matter.
Fact is, conifers are slow growing and we don't expect nothing nearly finished before 10/20 years.
Tropicals are fast growing (in tropical conditions) and can be pretty thick and in refinement stage after 5/10 years.
So when you buy a bonsai online, be careful, as many of the commercial vendors lie about the age of the trees as if it were important, just to charge more for your young tree.