The OP might be looking for a little market timing capability. I know in the last couple weeks with the given volatility - the market may have a large downward swing in a day or two - and then open up the next morning way up ... I would have enjoined tossing a few 100s, or 1000s if it was going down. Challenge though is with normal day to day functions - one is not monitoring the market all day.
Might be a fun exercise here and there with your play cash account - but its probably easier just setting and forgetting with DCO.
Beyond the "monitoring the market all day" problem, there's an even deeper flaw with this approach; it doesn't work. Or at least, it doesn't yield better results than just your normal bi-weekly pre-scheduled contributions. Many people have tried varying degrees of the approach to "invest immediately after the market drops X amount" and (spoiler alert!) they never pan out well. Why? Because you have to keep some cash on the sidelines waiting for those big drops. If it's only a small amount and/or if you only invest after a minor drop (say 1%... something that happens on average once or twice per week) it's not enough to move the needle. If you wait until much bigger drops and/or make bigger orders your portfolio starts to suffer from "cash drag"
Think of it this way - if this rather obvious-sounding strategy actually gave better returns than the benchmark, even by just a few basis points, a hundred savvy hedge-fund managers who actually DO watch the market continuously and actually CAN program in conditional buy orders, they would all be using this strategy.
Such 'strategies' emerge every couple years, but they always fall flat going forward.