Screw the Benzomatic type tanks and regulators with zero regulation capabilities. Get an oxygen tank from your local welding supply store and a regulator that is in Lpm (liters per minute). That will actually be 100000x better. You won't be wasting the little red oxygen bottles left and right.
Also, infuse oxygen BEFORE you pitch the yeast. Not after.
There are companies selling the oxygen wands (stone on a stainless wand). Those are typically 3/16" OD tubes. Same as the ID of your standard liquid tubing when kegging. So easy as all hell to get (by the foot at your LHBS).
With my setup, I set the infusion rate depending on the recipe/OG. Since I get my wort chilled in as little as five minutes (for ~8.5-9 gallons going right into the conical) it's not running for long. With the shutoff on the setup I have, I can stage everything and then simply open that valve as the wort begins to flow out the chiller. I turn it off when done, before disconnecting from the O2 bottle (I made a QD post adapter for my regulator).
Sure, you COULD do it the cheap and dirty way. I just don't see the point for that.
And I don't see the point of all that complexity
I would challenge you to be able to tell the difference in quality between two beers where one was fermented with whammadine exactly tuned oxygen flow rates to 10ppm from a welding shop vs hitting it for 15-20 seconds from a bernzomatic tank and hitting somewhere between 8-11ppm. My fermentations are healthy and take off within 3-4 hours.
You can make good beer without pure O2 at all, so it's simply not worth the effort to make it perfect when there's such a wide range of "success" criteria.
Infuse before or immediately after, there's no difference really the yeast is going to use it.
As for wasting oxygen bottles, I have used 4 in the last 1.5 years. Which equals $50.. So that's pretty darn cheap
But hey, we're homebrewers. I make beer for $20 a bottle when I could just buy it for $2/bottle. Overcomplicated is the whole point!