Sorry, I misunderstood as well. They mean to add chlorine a little bit at a time so as not to have the pH jump too high too quickly (for the reasons I stated). Adding enough chlorine that would normally raise the Free Chlorine (FC) level by about 4 ppm would raise the pH around 0.1 or so. That's about as much to do at a time. You always pour slowly over a return -- nothing new about that. The slowly they refer to is not to dump a whole bunch (gallons at a time) because that would raise the pH too quickly.
However, as you found out, the chlorine gets used up quickly at first because it is consumed by the ascorbic acid in the pool. So you can keep adding chlorine until you get a reading -- you don't have to wait in that case. Add enough to raise by 4 ppm FC, then wait 20-30 minutes and measure the FC. If you don't get a reading, add another amount to raise by 4 ppm FC, etc. Once you get a reading, you can wait to not add more chlorine until 4 or more hours later and you see that the water isn't colored nor any restaining is occurring.