Kakashi used Kamui several pages after he was introduced to Madara. That's not necessarily using it right away. Kisame can spam Suiro Sameodori because he has Bijuu-level chakra reserves, yet he doesn't. Why? Because, 99 percent of the time, the person whomever he would be battling would likely be killed in the process. Like I said, realistically in NV, this would not occur; even if it did, you act as if Kakashi's opponent would lie there awaiting his or her death, when this obviously wouldn't be the case. Itachi can use the Totsuka in the first second of a battle; he doesn't. Naruto can use a TBB in the first second of a battle; he doesn't. The list goes on and on. It doesn't matter whether they physically can or not. You should realize this. It took Kakashi, even when he wasn't IC against Obito, multiple pages to even begin to contemplate using it when he had full control over it. The only time a character is going to use their strongest, unbeatable technique is when we want them to. Odds are the opponent has either found a tactical counter to it or won't give them the chance to use it in the first place.
ThankYouBye.
