If you are going to switch it to a 5-1-1 you should bare-root it. Wash away all of the old soil beforehand, I just use a nozzle on my hose and spray off as much dirt as I can get off then swishing it in a bucket of water to remove the rest. If you skip this step your more likely to have root rot as the soil will retain more water than the 5-1-1 as well as you will have a hard time trying to figure out when to water. After your done and its in a new pot leave it in the shade for a few reeks while it recovers from transplant shock, then slowly move it into more and more direct sun over a couple weeks. Congrats on the new tree!