I do not see the relevance between any theory of Darwin and the presence of the Dajjal. The signs of the Day of the Judgment are part of the world of the unknown in its timing.

 

Since we do not have a clue on the time of the Day of Judgment itself, by default we do not have a clue on the timing of the signs minor or major. We can only call it when it happens.

 

 

In general, the presence of the prophet himself (Peace be upon him) was the first sign of the closeness of the Day of Judgment.

 

Almighty Allah knows best.