"Buying the dip" means when it dips, and you are reasonably sure its at the pivot, then you buy it. Now the dip might take a few hours to form or a few days. "Buying the dip" does not mean buying it after the first 30 minutes the market opens when there is a gap down with no obvious pivot. Its quite obvious to me that anything over 151 on the SPY will not be the pivot point.
I would buy it when I see it pivot off the 20 day MA. I have confidence that we will not see a 20 day violation anytime soon and I say that with two fingers crossed behind my back.