Here’s a long list of early electronic music: The greatest electronic albums of the 1950s and 1960s – The Vinyl Factory. (via Behind The Black.)
See also my Space Age Sounds section, which focuses on spacey sounding jazz-orchestral style music, usually with electronic sounds included, of the 1950s and early 1960s. This music is sometimes referred to as Space Age Lounge music. Some of the it overlaps with the Vinyl Factory’s list.
Here’s one of my Space Age Lounge classics: