Wearing only one at a time will not hurt anything but your upper arch may start to lag behind if you are going too long without it. This can become an issue depending on your individual teeth and where the teeth are more out of alignment. If your just doing this on the first tray or two it shouldn't be a problem and by the end of the 2nd tray you should be more comfortable taking and meeting with people with the aligners in. Just make sure at your appointment you inform your orthodontist that you are doing this and they will quickly be able to tell you if anything is not tracking correctly because of it.
