Green’s Dictionary of Slang

1. the starting time; at the start; usu. in phr. the first go-off.

1833		C.A. Davis Letters of Major J. Downing (1835) 49: In the first go off, you know, the General’s friends were all above matters of so little importance as Banks and banking.
1866		‘George Eliot’ Felix Holt I 243: That’s what I said at the very first go-off.
1872		in ‘Mark Twain’ Life on the Mississippi (1914) 459: [as spelt] ‘i guess you thought i did not cair for what you said, & at the first go off I didn’t.’.
1885		A. Griffiths Fast and Loose III 217: It will depend on whether I can elude his eye for long enough the first go-off.
1899–1900		C.L. Cullen Tales of the Ex-Tanks 88: Who wants to listen to a lot o’ slush [...] it sounds too much like beery ballads from the go-off.
1918		K.F. Purdon Dinny on the Doorstep 91: But it ud be as good tell her, the first go-off; then she couldn’t go fau’t ye, after!
1922		Joyce Ulysses 573: Corley, at the first go-off, was inclined to suspect it was something to do with Stephen being fired out of his digs.
1934		D.L. Sayers Nine Tailors (1984) 117: Deacon didn’t explain, first go-off, how he happened to be in Mrs. Wilbraham’s bedroom at all.
1947		J. Maclaren-Ross Of Love And Hunger 209: I had a visitor. Heliotrope. Didn’t recognise him first go off.
1977		Fidrych & Clark No Big Deal 110: He literally told me, right from the first go. He said, Your knuckleball ain’t gonna do it.

2. one who runs away, abandons the group.

2005

B. Hare Urban Grimshaw 148: Urban and I were go-offs for clearing out and leaving everyone in the lurch.