~Any bonsai tree takes years to perfect.
~The best way to shorten the time is, growing an apple tree on bare ground (this is where the plants grow fastest, not in pots and definitely not in tiny bonsai trays..) and then when the trunk has reached a desirable thickness, you can remove the tree from the ground and plant it in a bonsai training pot (or a normal large pot, unlike a tiny bonsai tray..)
~Then you can start basic styling of the tree.
~Let it grow and be shaped as years pass.
~Finally when it has reached or almost reached your expected shape, plant it in its bonsai tray.
The whole thing will take about 10-20 years i guess..
I dunno that depends on how fast your original apple tree grows. I have grown an apple tree from a seedling in my garden and it's been like an year. But it is still a tall but hideously thin thing that is totally not ready for bonsai training..