There really is no wrong way of using gelatin as long as you cold crash.
When I'm doing it, I cold crash for 2 days, remove it from the fridge and add the gelatin. Haven't had any problems doing it that way. But a case can be made of adding the gelatin and then cold crashing.
In any event, cold crashing is a must to get the full effect of the gelatin.
I've only used gelatin once, and in my opinion, with a good cold/hot break paired with some Irish moss, you don't really need the stuff. Although it adds no flavor, I prefer to make my beers with the most minimal ingredients.