Hi, my name is So Close, and I admit to attempting to time the market (just a little).
Like most, my 401(k) is on a fixed schedule so no timing there, but I have tried to time my taxable/IRA buys for the little bit of excitement I get from "getting a good deal". I'd say I've probably done a poor job with the IRA's (need to quit) as I have tried to wait for larger dips (5-10%) that have never come, or come and go so fast that I miss the opportunity (last year's ebola scare for example) but while I don't have any records to support it, and like all gamblers, I feel like I have probably come out a little ahead with my taxable purchases. Basically what I do is sit on a purchase for just a day or two if the market has moved up for 2-3 days in a row as usually some profit taking takes place and the market dips a bit, my signal to buy. A "win" is usually around .25-.5% or so on the purchase, but I have certainly "bet" wrong on occasion as well, or missed the cutoff due to being in a meeting, too busy to check the market, ect.
Let's say you gave yourself a one week window to make your purchase, even perfectly executed, you would probably only add a few grand to your stache over the accumulation phase using this method. Your time would certainly be much better spent churning credit cards or learning some other value adding skill. For me, all it really is, is a little entertainment that helps the day go by, not some way to supercharge my stache. Once I buy though, I am pretty much in it for the long haul.