Our field is now very specialized, and the advice that you must work med-surg first does not seem applicable now. I understand the context in which this advice was useful, but it doesn't seem to be today. Today, it makes as much sense as an aspiring neurosurgeon to first specialize in family practice. Although both need a similar educational foundation in the beginning, they need to branch off to learn specialties.
I believe this is one of the issues causing problems in nursing education. We are increasingly specialized, and although we share common basic skills, each area of nursing is so different. These fora frequently have threads that comment on how new grads aren't prepared to "hit the floor running" right out of school, and yet we continue to prepare nurse generalists. I do wish there was a more formalized nursing residency program that could allow a nurse to feel more confident in his/her chosen specialty, but that is an entirely new thread.
As an educator, I see many graduates who believe that they must first be in med-surg, although they hate the area and want to work in another specialty. They often quit nursing prematurely because they are unhappy in med-surg. I will say that having worked in a variety of specialties over the years, that med-surg nurses can prioritize competing demands with the best of nurses. They often have incredible time constraints and high patient to staff ratios. You see a wide variety of conditions in med-surg. Can working in med-surg improve your skills? Absolutely. I performed the most wide variety of skills in ER, med-surg, and ICU. What you might want to consider is whether the benefits would outweigh the fact that you enjoy psych. In your post, you said:
-"I'm so excited..."
-"Psych is what I want to do..."
It seems as if you already know where your passion for nursing lies.
Although you will encounter psych in every aspect of nursing and in every specialty, we need excellent, caring psych nurses. It is difficult, and one of the only specialties I've never tried. One of the things I love most about being an educator is seeing my students right before they graduate. I have known them for three or four years, watched them grow and learn. When they find an area they love, there is a sort of "settling in" or a "click" I can see. I know they are happy, and they just seem to excel in that area. I LOVE when my students find the area(s) of nursing that make their career meaningful and not just a job. I love to talk to them years later and know that they are happy. They often ask me this same question: "Do I have to work in area x for y years?" I tell them that they need to pursue what they love. If you ever feel you lack skills in a certain area, you can always work a per diem job in the area you feel you lack. The majority of time should be spent in an area you love. There is such a sense of satisfaction watching my students find that area, and to know they will have a long and productive career, instead of a "job" that they hate. I would wish for the same happiness for you.
It was this way for me in my specialties. Do I hate my job some days? Absolutely. But the majority of the time, I wake up and think "I GET to go to work" and not "I have to go to work."