Those instructions have been well thought out by the manufacturer and should be followed. I apply bluing by using a Q-tip on small sections at a time. Within a minute I rapidly rub it with a paper towel. I was shown this by my uncle over 30 years ago. Why the paper towel works best I couldn't say, but it does. I've tried every which way to cold blue and found this method to be superior. Maybe it's a chemical reaction, or just by rubbing fast causes friction thereby generating heat. This step can be repeated as many times as you feel necessary till the finish looks even.
To finish it off use only oooo steel wool like they use in museums when restoring firearms, cause it doesn't remove any finish and from what I can tell it seems to help the bluing adhere better to the steel and really looks good. The more you polish it with the steel wool the shinier it gets. I found this method to be the most durable and seems to hold up best. You can try this cause there's nothing to lose and everything to gain. Good luck.