Douglas Harper's Etymology Dictionary
go ahead
as a command to proceed, 1831. As an adjective phrase, by 1840.
Wiktionary
go ahead
vb. (context idiomatic English) To proceed; to begin.
WordNet
go ahead
v. proceed (with a plan oc action); "He went ahead with the project" [syn: plow ahead]
Wikipedia
Go Ahead (band)
Go Ahead was a band formed by Grateful Dead members Bill Kreutzmann and Brent Mydland in 1986. They performed up until early 1988. The band also included Alex Ligertwood and David Margen who were members of Santana.
Usage examples of "go ahead".
Send the rest back down and we'll go ahead with the battle plan, take the Salamis.
The coloured folks there like to be by themselves, so we just let 'em go ahead and don't bother with 'em.
Let me go ahead and pull out in front of this guy to slow him down.