Sometimes "immediately" takes into account the two week notice. Another thing do is put jasmine essential oil on the collar of my shirt. Jasmine tends to calm me down. I get early to my interviews, but I stay in my car listening to relaxing music. I check in 5-10 minutes before.
If you are still interested in the job, write them a thank you email. If you have everyone's email that's even better. It shows your interest and attentive skills. In the thank you note apologize for the scheduling confusion. Say something like you realize they are very busy people and you don't want to waste their time. Then spend a paragraph with the highlights of the interviews, things they might have indicated they like. The next paragraph talk about you. Acknowledge this will be your first job in the field, that you are very dedicated and not afraid to put in extra time to meet the learning curve. Tell them something unique about you that you will bring to the job. Finish off by thanking them again and offering them the opportunity to contact you if the have additional questions or need clarification. Repeat again "I am looking forward to bringing my skill set to your organization and being a part of the outstanding service they provide".
Let me know if you need help. Glad to do it.