Wait two weeks.
It's tempting to want to check gravity early and often, but you're wasting good beer.
The goal when you check gravity is to determine when the yeast is essentially done fermenting so you can move on to the next step, whether it be lowering the temperature to age it for a while or simply to bottle if it's a beer style that's best to drink without aging. There's no way your beer is close to done at 4 days with krausen still on top. I would at least wait until the krausen drops and the beer clears a little. Then take your first gravity reading. Three days later, take another. If there's no change, and it's reasonably close to your expected final gravity, it's probably done.
Oh, I do sometimes cool the sample when I taste it. I usually first taste it warm, since it's easier to pick up off flavors when it's warm. But I sometimes taste it cold to get a better idea of what it will taste like at normal serving temperatures. But at four days, I can just about guarantee you it will taste weird.