Its great that you want to engage in a career path now.
There are many variables behind the scenes that you as a trainee will have no direct control over in terms of what will happen to you in the pipeline in regards to nuke life:
1. Your rating (MM, EM, or ET). Now, when I joined there was a shortage of MMs so I could guarantee MM during boot. However, you will find out if you can choose any particular rating during your boot camp in-processing. One day, all the nukes in your boot camp division will be marched over to some office to do some nuke paperwork. All the rating stuff will happen there.
2. Your class start date. Ok, you graduate boot and are whisked off to beautiful and balmy Charleston, South Carolina to begin your A-school training. If a class of A-schoolers just started, you may be doing none-nuke training until the next class forms up (waiting on more arrivals from boot camp). This none-nuke training will most likely involve cleaning something and being bossed around by none-nuke enlisted building managers who have nothing better to do then be mean to nukes that willmost likely be of equal rank to them in less than 2 years time.

Caution: During this down time you may feel antsy, nervous, ready to start nuke training, bored, pissed off, FTNed, or in close proximity to bad nukes who are on restriction and quite possibly on the way out of the nuke pipeline en route to a life of scraping and painting various metal things. During these times many potentially good nukes find themselves in bad nuke situations and due to lack of foresight, become bad nukes. Therefore, of you find yourself in the wrong crowd, leave the crowd.
3. Your class starts. Yea, have fun and study. Graduate, get your chevron, go to Petty Officer Third Class Indoctrination training. Pat yourself on the back, you deserve it, get ready for round 2.

Caution: Time for more cleaning. See you may either be the last graduating A-School class to form up with the other graduated A-school classes to form up an entire Nuclear Power School class OR you may be waiting for more A-school classes to graduate. So basically there could be a week or lotsa weeks between graduating A-school and starting NPS. It all depends on timing. So, more cleaning possibly and other infrastructurally necessary duties to keep the big machine turning.
I was doing this for about 7 weeks. Keep sharp. Keep motivated. Stay out of trouble.
4. NPS begins. Yea, have fun and study. Try and graduate in the top 50% or better. Graduate. Pat yourself on the back, you deserve it, get ready for round 3.

No more barracks, gotta find an apartment or a house to rent either in SC or NY depending. You by now have formed a close relationship with a few guys that you can trust. Become roommates or find your own place.
5. Prototype. This is where the choices begin that will make or break your chances to be an instructor. The first step was actually making it to prototype having graduated in the top half of your NPS class. Now its time to seperate the wrench turners from the theory-jockies. You better impress the heck out of your been-there-done-that-used-to-fish instructors. You may ask, "How do I do that?". "Well, for 19.95...." No, seriously, its really quite easy:
1. Be 15-20 minutes early for everything scheduled.....coming to work, classes, small group exercises, 1-on-1 training.
2. Work tirelessly to stay ahead of "The Curve". The curve is this imaginary monolithic structure that make apes pick up bones and kill each other

The curve is just a projected level of completeness you need to be at in relation to your specific prototype class of MMs, EMs, ETs respectively. You want to be at least 10% or more ahead of "The Curve". Think of the curve as a savings account. The farther you get ahead of the curve, the more money you have in the bank. Maybe one day you lose your job or in relative turns, the prototype reactor has to shut down for some reason and the training progress slows too. Well, if you had no money in the bank and lost your job, life would suck. If the training tool goes away and you are straddling the curve, you will soon be "NEGATIVE". Don't be negative, ever. Being negative is like being financially in the red.
Bad ju-ju.
But how do I get ahead of "The Curve"? Really easy.
a. By working tirelessly to get check-outs, by putting in extra hours, by setting the example for your peers, by impressing your instructors, by bringing candy to check-outs.
Aside from the candy, all the preceding stuff will motivate your instructors to facilitate your qualifying ahead of a more shit-bag type trainee.
3. Uniforms: Keep them inspection ready. Have a uniform you don't mind getting dirty "On the boat". Have seperate uniforms you wear in the off-hull building. Maybe you are covered in grease because you just got off watch, but is that the presentation you want to make in the training environment to people that may think you just look like shit rather than knowing you just got off watch?
4. Now, following all that advice, you have done EVERYTHING in YOUR power to make yourself look good for: Officer programs, being selected for staff training right after graduation (staff pick-up), or an extra school if you are an MM (Welder or ELT). You've kept your nose clean, studied hard, shown respect, maintained a nice uniform, qualified early, stood watch, gave a sea-returnee time off watch because you qualified to stand his/her watch, and are now a useful nuke. You are done.

But you were not selected for anything? Why? Who knows, maybe there is a new ship needing extra manning, maybe a bunch of senior guys at sea got discharged, maybe there were candidates better than you. Who knows. These are all those intangible behind the scene things you are not privy to and have no control over. Do you become imbittered? No, you take your ethics to sea and keep on plugging. A nuke like you is bound to succeed and become a stand-out somewhere.
Acting the same way at sea will make you eligible for all the special programs you want.

There are many things I have not covered, but its beyond your level of concern right now. So much of th pipeline is situational and cultural that I could not begin to describe the finer points in a way that it would make any sense to you. Just follow my advice and you will easily figure the rest of out for yourself.
Good luck.