This isn't really answerable, because different people get different symptoms. Also, anxiety attacks come in two categories: the episodic or just a couple of times in one's life type and the chronic type. If you are getting chronic anxiety attacks, you're probably feeling very anxious for a while before you do the thing that's triggering the attack -- by the time you get to the trigger you've been building up the anxious thinking for a period of time so the attack is the culmination of the process, not the beginning. The only thing that matters to your personal recovery is how you feel, not how I or someone else feels, because you need to work on the symptoms you're having. For example, if you are seeing a psychologist who actually knows how to treat anxiety, there are certain techniques that are used to help you relax, but which ones will often depend on your particular symptoms. Some people, for example, hyperventilate, so working on their breathing would be more important than in those who don't have an such noticeable problems. Probably the only symptom common to everyone is thinking very anxious thoughts, but the rest is all over the place.
Your first symptom would be your mind racing and your heart racing. Your going to feel like your going to pass out. Your going to be over thinking yourself and crazy thoughts will be in your head.