inicio, noun:

beginning, start

Related to the verb iniciar to begin, is el inicio, beginning, start.

desde el inicio de 2006
since the beginning of 2006

Quite often it’s used in the plural, where English more naturally expresses the idea in the singular.

Lo han apoyado desde sus inicios.
They’ve supported it from the beginning.

You also often use inicio to talk about the beginning of a course of study:

Está previsto que finalice* a mediados de septiembre, a tiempo para el inicio del curso escolar.
It’s expected to finish in mid-September, in time for the beginning of the school year.