So I brewed a German pilsner Sunday morning and had it in the fermenter and down to 50* by 4:00pm. I boiled about 1.5 cups of water and cooled it down to around 75*. I put two packets of 34/70 and the boiled water into a sanitized mason jar. I swirled it around to get all the clumps dissolved and let it sit about 15 minutes. I hit the wort with oxygen through my diffusion stone for about 75 seconds. I was at the bottom of the oxygen tank because it was a pretty weak stream of oxygen coming out. I then pitched the yeast into the wort.
Fast forward 40 hours and there is no signs of fermentation. No krausen at all just 50* wort doing nothing. At what point should I consider pitching a couple more packs of yeast? And if/when I do, would adding more oxygen be a bad idea?