When did the theory of Evolution become a fact and not a theory?

Definitions:

The Fact is what you can observe (experiments, fossils, mutation in microorganisms etc.)

The Theory is the explanation of the fact.

So

Evolution has been a fact for at least 3.6 billion years on Earth (the earliest known fossil evidence of life on our planet).

Evolution has been a theory for 150 years (Darwin's natural selection was the proposed explanation)

Moreover:

Evolution has been a hypothesis for 2500 years (see B K 's great answer)

Evolution has been a law for 200 years (Lamarck's laws of use and disuse)

Evolution is a historical hypothesis. The claim that it is a theory, or even a scientific theory, are both false claims.

The idea that Evolution is a "Fact" is a tactic to persuade you to accept Evolution as true without giving you the proof or indeed any evidence. Just call their bluff and ask for the proof, but be prepared for a display of the Ad-hominem fallacy.

Scientifically, evolution is still a theory, but one which has never been disproved.

There is no point in time that can be pointed at, much like asking when the automobile replaced the horse.

It occurred gradually, as the evidence in its favour increased, beginning with the fossil evidence, and stratigraphy.

Publication of: "On the origin of species", by Charles Darwin, on November 24, 1859, can be considered as the beginning.

The discovery of DNA as the means of the transmission of genes, by Watson and Crick, in 1953 was seminal, but since then DNA analysis, radioactive isotope decay, photoluminescence, electron spin resonance, and geomagnetism has slowly built up an irrefutable, mutually corroborating body of evidence.

Evolution has been known about since the times of the Ancient Greeks. Anaximander (circa 520BC) was the first to propose that animals and humans evolved from other creatures.

Darwin was the guy who gave us a scientific explanation of how evolution might work. His theory of Evolution (or Common Descent) by Natural Selection.

The evidence from modern scientific experiments since Darwin leads us to believe that Darwin was right. It has been confirmed by recent genetic studies and the various gnome projects. If there was a specific time you could link Darwin's theories to becoming scientific fact, I'd say it was probably when the double helix structure of DNA was first discovered by Watson and Crick in 1953. Although they did not discover DNA itself. Although the fact of Evolution itself has been known for much longer - through other methods such as the fossil record.

Evolution is divided into two parts: macro and micro. Micro evolution is a fact, whereas micro remains a theory because we can't trace the exact steps of the evolutionary process of the three trillion species on earth.

Problem: Evolution remains a theory, because it can not be tested by experiment. And secondly, never in the fossil fields nor today has any animal or plant changed from one species into a totally different species.

You clearly do not understand the definition of "theory" in scientific terms. Theory does NOT mean what it does in popular speech (as in "I have a theory about who stole my cookies".

In scientific or technical terms, theory, principle, and law represent established, evidence-based explanations accounting for currently known facts or phenomena or for historically verified experience: the theory of relativity, the germ theory of disease, the law of supply and demand, the principle of conservation of energy. It simply describes an organized system or process that has been deduced and quantified by repeated observation and evidence.

When genetics and fossil evidence were able to support the theory.

Once people actually read Origin of the Species, and woke up.

Charles Darwin basically explained that animals find mates with physical evolutionary potential more attractive, and thus they survive and become the new species.

Idk about the year, sorry.