The goal is to keep your nitrates no higher than 40ppm above your tap water.
You definitely need to do a massive water change at the end before you add the fish. And yes, 7 days is considered best, but 5 days is the minimum. You might not hit double zeros again tomorrow. It's seems strange, but these are biological processes, more than they are chemical, as much as we are focusing on the chemicals only. They might slow down for a day or so before going back to double zeros. So, if you don't get doubles tomorrow, don't let it bug you.
What is your stocking going to be?