Depends on what being able to communicate with animals truly entails. If I can essentially blend myself into every animal culture and use them to my will, probably that one. If being able to communicate with them though just means that I know exactly that the lion is saying, "I AM ABOUT TO RIP YOUR FUCKING THROAT OUT AND EAT YOU!" moments before he rips my throat out and eats me, the human languages.
Probably when. Then I know at least when I need to complete my bucket list by. Plus, if I chose "how" and the answer was, say, "getting hit by a bus," I'd basically be afraid to ever go outside again, and would be a shut-in until the day finally came where a bus came crashing through my house and killed me.