No the 48 hour "cycle" period is a myth, that does absolutely nothing for your fish. Of course it's going to read all levels safe, there's no fish in there to create ammonia to start with!!!
The Nitrogen Cycle is what you want to do, it's going to take about a month. What you're doing is growing a colony of Beneficial Bacteria or BB. For BB to grow they need ammonia and then they turn that ammonia into nitrites and then finally into nitrates which are safest for your fish, nitrates are taken out with water changes. That's why it's important to do your weekly water changes so that you can take out the Nitrates which can still harm your fish.
So looks like you'll be doing a "Fish-In" cycle which means you'll have your fish in there while your colony of good bacteria grows in to keep the fish safe. You will need to test for ammonia every day or every other day for a month, DO NOT let ammonia go over .25 ppm's, it can harm your fish and it is very stressful for your fish. Look at that link that I gave you and go to comment #4.
If you notice your ammonia getting over .25ppm do a 50% water change, wait an hour and test again. If it's still .25ppm or over then do another 50% change.
Also do not use AQ salt for prevention, it does NOTHING for your cycle. When used long term for Betta's, even at a low dosage it causes liver/kidney failure which is Dropsy. So in order to avoid that, NEVER use AQ salt more than a 14 day period and never over 3 teaspoons/gallon.