People are always in a hurry to get their tomato plants in the garden. It is the #1 favorite food to grow. But all too often the support is added too late. The time to put your tomato cage in place, is soon after you've got the plant in the ground. I know what you're thinking...I've got plenty of time. But you don't.
In addition to amending all the vegetable beds with rich organic matter every spring, I want to give the tomatoes every possible advantage at the time of planting. I pinch off all the branches on the bottom half of the stem. Dig the hole and remove 4-5" of soil and set aside. Then I mix in 1 cup of a granular organic 3-3-3 fertilizer with the next 10" of soil. Place the plant down in the hole and fill in with the soil I first removed. I bury between 1/3 and 1/2 of the stem below ground, which will give my tomato plant a much stronger root system. Mulch around the plant and give each tomato 1 gallon of water.
I believe in tall tomato cages; these are 6' plus. Frankly, those little wire cages at 42" and 54" are not nearly big enough. By the time you push them down into the ground, they are only 3-4' tall. The plant will grow to the top, then drape down on itself and continue growing. There is no way for air to circulate in conditions like that.
Do yourself a favor and get those cages over your tomatoes now. Don't wait until you are fighting the tomato for placement and breaking off branches in the process. You won't be a happy gardener then.