It stabilizes at external pressure, in 40sec or less.
Air pressure at 30kft = 4.37psi, cabin pressure at 8kft = 10.92psi, from a calculator the flow rate through a 12in orifice at this differential = 475cuft/sec, volume of 737-700 cabin = 9000cuft, time to expel cabin volume holding all this constant = 19sec. Double this time for a linearly decreasing pressure differential.
Commercial aircraft exchange their cabin air 10-15 times per hour, or once in 4-6min, so the pressurization system will not be able to come anywhere close to keeping up. Without descent the cabin reaches external pressure in about 40sec. With descent it is even faster as the differential is lower, and therefore reached sooner.
There was a question about the source of the calculator flowrate. I looked at three: