I kind of remember an article about over-aeration, something like yeast will keep reproducing in an oxygen rich environment and create an off flavor like overpitching does. Not to mention oxygen can be toxic to yeast at high levels, which begs another question, what is the o2 saturation point of wort and would it be high enough to possibly damage yeast/flavor?
There's an article here on HBT that talks about oxygenation time and dissolved ppm https://www.homebrewtalk.com/f163/o2-results-my-new-o2-meter-318420/
My experience is that oxygen rapidly comes out of solution in wort. I measure my wort oxygen levels with a high quality dissolved oxygen meter. I personally don't believe, in homebrew applications, that oxygen toxicity is even possible. My suggestion: single dose oxygen in regular beers, double dose oxygen in big beers anywhere from 6 hours to start of fermentation.
White and Zainasheff had a lot to say about the whole oxygenation thing in Yeast, and while they claim it is pretty hard to actually inflict yeast mortality with high O2 levels, over-oxygenation does have detrimental effects (including excess fusel formation). That chapter alone is worth the price of the book, imo...
I have been giving the wort a blast immediately (minutes) before adding my yeast starter. Activity is noticeable at the soonest 12 hours later (usually a day). I wonder if I should hit it with o2 a few hours after yeast is pitched if it dissipates quickly instead of prior to pitching?