One thing we learned in our routine checking of gas prices for Xodooz.com | EDSA is that gas stations do not really adjust their prices at the specified time of an oil price adjustment (OPA). Some adjust their prices earlier, and some do it later. (It's not to say though that they increase their prices earlier, and roll them back later.)
So before taking advantage of tomorrow's OPA, either by gassing up early to avoid the diesel price hike, or by gassing up late to get a better price for gasoline, make sure they haven't yet increased the diesel price, or make sure they have already lowered the gasoline price by checking gas price billboards or simply by asking your gas boy (which might not be reliable at time because some of them don't really care).