At some point, "get go" and "get-go" will be.
Doesn't make it any less ugly and cringe inducing so NickNack is quite entitled to his express his ire, but, given the way language works, there is every reason to hope that it, like many other fashionable, slang even "formal" words and phrases before, will wither and die.
Doesn't make it any
more ugly and cringe inducing either. Only NickNack's unqualified opinion does that.
NickNack's misplaced assertion that some phrasings are objectively less valid than others -
with no reason quoted - does not entitle him to express his ire. Saying what the problem actually is - rather than simply stating that there is a problem - is required for that.
My ire, on the other hand, comes from witnessing empty snobbery that masquerades as taste. From the impugning of a richer pool from which to draw a variety of expression, for the supposed reason that it is, supposedly, wrong.
Heaven forfend we should have a choice of phrases! Let's all speak using only the words which are arbitrarily determined to be the pinnacle of correctness, despite the non-existence of that concept! There was an exact point in history when we got it right, and it's a travesty to use any coinages dating from after that sacred moment! Burn the thesaurus, for only the pure core of meaning (which is somehow inherent within the words I like but not the ones I don't) shall be allowed to exist! Slay the poets, for expression must be limited and formalised!
Cobblers. Say "get-go" if you like. Or "outset". Or "off". Or "inception". Or so many more things.
And don't try to be a snob about semantics on a grammar forum.