yes and no, if you disconnect it at 1 week at 15 psi, and the beer has only absorbed the about for, let say, 10 psi, then there will still be 15 psi of pressure in the headspace that will be absorbed. So if its not at its full carbonation level, it may increase a bit more, but not much. You shouldn't have to disconnect the gas though, because when you pour a beer, the pressure will drop. So the regulator will keep it pressurized at 15 psi throughout the life of the beer in the keg.
Under-carbonation is easy to fix, over-carbonation is a pain. So what I would probably do is set the pressure lower to start with, like 10 psi. Once it has reached its full carbonation, see how you like it. If the level of carbonation is good, leave the gas connected and keep it at 10 psi. If you want more carbonation, then bump it up a bit to maybe 13 psi. Let it sit for a couple days to absorb more CO2 from the higher pressure, and check again. Keep doing so until you reach the carbonation level you like.
If you set it to 15 psi and find that the carbonation level is too high, then you would need to vent the pressure off several times over the span of several days, to basically "flatten" the beer back out. It's a pain.