Depending on how big a tree you initially get, it can take 7-8 years to get a tree that is 4 foot tall.
My advice is to talk to someone locally who prunes Christmas trees. The way you keep trees nice and bushy for display is to do some judicious pruning while the candles (the new needles) are growing, which is about now in central PA and is probably the same where you are in Kentucky. While the candles are growing, the tip end (apical meristem) produces hormones which suppress the development of dormant buds in the tissue along the stem, That way, all the plants energy is sent out to the tip creating a longer and straighter branch. If you prune the candles while they are still light green, the effect of the apical meristem is removed and small dormant buds form all along the remainder of the candle. Next year, these buds will become new branches, thereby redirecting the upward, straight growth of the candle into many smaller side branches - filling in any gaps in the trees foliage.
I found this online which has some very good and precise recommendations for your state. Hope it helps.