When I chop down trees in Don't Starve, I always expect something to attack me like a sudden Tree Ent spawning. I will feel safer if I know when a Tree Ent will spawn. So what's the chance that a Tree Ent will spawn?
Treeguards do not normally spawn before Day 3, after which each Evergreen at any stage fallen has a 1.33% chance of spawning one from a nearby Evergreen tree. After Day 30, up to two Treeguards may spawn at once, with up to three spawning after Day 80 given enough Evergreens nearby.
I assume you meant Treeguards not Tree Ents. You should never feel safe, RNG is never on your side.