Nomination is if you receive one from your MOC. An appointment is what a SA will offer if you are accepted. You must have a nomination to be appointed.
Each MOC will have his/her own time table. Find the website for your own specific district congressman and both U.S. Senators, and search for their service academy page. They will spell it all out for you.
I also suggest you go through the Nominations forum here: https://www.serviceacademyforums.com/index.php?forums/nominations.21/
And also the stickies at the top of the page. You should also read through the web sites of the academies you hope to attend.
There is no such thing as a stupid question.... but I have to say that asking such a fundamental question indicates to me that you don't do your homework/research first. We're happy to answer anything here but you should do some research first. It will certainly be expected of you at any service academy and while on active duty.
The nomination and application process is long and drawn out. I would suggest that you take some individual initiative and make sure you understand the process. The answers to your questions are readily available on the Academy's or MOC's website.