I'd hookup the CO2 and purge the keg. Pressurize to 15 psi & vent. Do that 3 times & you'll have most of the air/oxygen out. Then leave it to carbonate. You can force it later if necessary.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
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