Buying new apple trees
I have a small paddock area that I am planning to put in 3 apple trees, (or maybe 2 apple and a cherry) this winter. I understand the issues around pollination well enough to get me going, my question is around tree size that I buy. From what I have read, its better to buy young saplings as these get going quicker and adapt to the local conditions better, but I don't really want to be waiting 5 years for my first apple. What is a good trade off here - what size / age do most amateur gardeners buy trees?
Any other hints are words of advice in this area would be greatly appreciated