Stage 1: You leave the house, oblivious that anything is wrong. You may even think, "Wow, wouldn't it be terrible if I left my phone at home?"
Stage 2: You need to do something phone related. Time to start fumbling through your pockets/stuff.
Stage 3: You continue to look through your stuff, in denial, because maybe your phone is not still at home?
Stage 4: Your phone is still at home. You very quietly plot your own murder.
Stage 5: You agonize for five minutes over whether or not to go home for it.
Stage 6: You courageously decide to go on without your phone, with such lies as "I'm at work/school to do work/learnin'" and "All the people I'd want to talk to will be at the place I'm at, anyway."
Stage 7: You start to see your lack of a phone as a badge of honor. And you become that annoying person who tells others that "we're too focused on our phones, guys."
Stage 8: You realize that without your phone's GPS, you actually have no idea where you are going.
Stage 9: You discover that you now have no prop to help you avoid eye contact with people.
Stage 10: You realize that all phones that aren't yours are basically useless to you, because you only know two numbers by heart.
Stage 11: You remember all the lines that you will have to wait in today. You have no idea what you are going to do with yourself while in line.
Stage 12: You see something goddamned amazing and know that you can't Instagram it.
Stage 13: You find yourself in a circle of people who are all buried in their phones. They are laughing and learning and enjoying themselves, and you feel very left out.
Stage 14: You accept that not going back home for your phone was actually a pretty terrible idea.
Stage 15: You return home, and see no missed calls. You do not know whether or not to be relieved or depressed.
Stage 16: You realize that you don't need any friends, because you are just so happy to be reunited with your BFF, your phone.
