I don't know what they are talking about honestly.
For the record I'm not really recommending SafeStart, but if you do want to use it, it doesn't really matter when, except that I wouldn't do ANOTHER water change until at least 24 hours afterward to give the bacteria time to be moved through the system and "stick" to the filter media
None of the other recommendations make any scientific sense to me. Is Aqua Safe just a water conditioner? Even if it locks down ammonia, it's still a form that the bacteria can eat.