No ... Koresh was an offshoot from an offshoot of an offshoot of the Seventh Day Adventist.
The Branch Davidian Seventh Day Adventists (also known as "The Branch") are a Protestant sect that originated in 1955 from a schism in the Davidian Seventh Day Adventists ("Davidians"), a reform movement that began within the Seventh-day Adventist Church ("SDA") around 1930. The majority of those who accepted the reform message have been disfellowshipped (excommunicated) due to many in the leadership of the SDAs rejecting it.