First appearance: New Fun Comics #6 (October 1935)
Dr. Occult would be in one-page features for four issues of New Fun Comics (which soon changed its name to "More Fun Comics") before increasing in length to two pages per an issue for a while.
By the end of his run (which was in More Fun Comics #32, cover-dated June 1938), Dr. Occult's feature had grown to be four pages long.
And from Who's Who: The Definitive Directory of the DC Universe Vol. VI (August 1985):