Well, it looks as though you've discovered that Reef2Reef is a great place to come for advice ... sometimes too _much_ advice!
Pretty much everything everyone has said is true, even though some of it sounds conflicting. So what's "best"?!
That's going to be a different answer for each tank and for every reefer. Below, some things off the top of my head that worked for me. (Please excuse me if I seem to be "mansplaining" - I don't know what you know, but I do know that a lot of information all at once, such as a new reefer experiences, can be confusing.)
Your two bottles will both help you deal with ammonia, a fairly toxic waste product of fish. "Nite-out" contains nitrifying bacteria (though it's not a brand I've used - I've only used Microbe-Lift's "Special Blend", and bacterial products from other companies). A lot of folks swear by "Dr. Tim's One-and-Only" and SeaChem's "Bio-Spira". Both are bacteria in a bottle, and both work well. .... Wait. Are we throwing _bacteria_ in our tanks?! Yes - these bacteria feed on ammonia, converting it to less-toxic nitrite, and even-less-toxic nitrate. Nitrate can be removed from your system by algae, by partial water changes, and by even more bacteria, these guys living deep within your liverock. They'll convert the nitrates to nitrogen gas.
"Prime" is for emergencies, primarily, and can help neutralize ammonia in a tank that already contains fish and other livestock.
You've added some liverock, you can go ahead and pour in some of the bacteria and something for them to convert. A table shrimp (buy a bunch and have scampi or stir-fry for dinner tonight!) can do the job, as can dropping in some fishfood, as though you already had fish in the tank. (Keep in mind that if that fishfood goes into your filter, it's still in your tank as far as producing ammonia goes!) You can also use _pure_ ammonia - don't use any ammonia you might find at the local market which contains "surfactants"! Those, you don't want in your water.
Next, you'll need some test kits - Ammonia and Nitrate are important ones, and they'll likely come bundled with a Nitrite kit. (It can be helpful to watch the nitrite level during your cycle.) Test the water regularly - daily isn't too much during your initial cycle. You'll see the ammonia level rise - sometimes off-the-charts - and then fall. (In my tank's case, the fall was almost overnight.) You'll see the nitrite rise, following the ammonia's path - and after the ammonia falls, the nitrite should follow a few days to a couple of weeks later. Finally, using your trusty test-kits, you'll see nitrate levels rise steadily. (Denitrifying bacteria deep in your liverock take longer to get cranked up.) Nitrates are _much_ less toxic to fish, but corals and invertebrates aren't big fans, so now's a good time to prepare a water change to lower the nitrate levels and start thinking about your first living creatures. (You may already be seeing your first algaes - welcome them!) Go slowly with adding life, keeping an eye on the ammonia level (should _always_ be zero after your cycle - if not, consider it a clear warning of impending danger!) and your nitrates. _Seriously_ consider some kind of quarantine protocol for every living creature you add, in order to prevent disease from entering your sparkling small environment and mucking up your week.
Oh - and there's this thread:
https://www.reef2reef.com/threads/the-supreme-guide-to-setting-up-a-saltwater-reef-aquarium.138750/
Enjoy the learning that is continuous, and the community that is reefing!
~Bruce
