the DIP category actually depends on each person how to judge it. so if as you say, it could be a 1% or 2% drop from ATH according to you it is already DIP. yes, and that can happen if you keep bbitcoin for years until bitcoin touches the new ATH several times. but for me personally, DIP is wider or when bitcoin corrects deep enough from ATH.
and what I mean by buying the whole here is not buying all the bitcoin available in the market at that time. if you are a so-called whale it might be possible. but what I mean is buying the whole 1 BTC alone not split into small parts.
there's a strategy I learned from sir JJG , is about spreading out your reserved funds to buy the dip without going all at ones. Like most time that dip we may consider the dip may not be the dip , like for instance when bitcoin price dip from the price range of $73k to $65k alot of individuals may think that $65k is the dip stop , before the price would surge again, then lateron it experience further Dip to price range of $58k . So instead of buying all the dip at once you could spread out your reserved funds like buying the first dip with some certain percentage of your reserved funds and lateron if it further dip you could still purchase with another percentage of your reserved funds. Like doing DCAing without waiting for weekly or monthly to buy.