I give mine a couple hours at the very least. Just move up slowly. Up your bass every hour. Make sure your gain is set before upping your bass also of coarse.
If you pay attention, many subs will make audible changes in their output (both freq response and increased output levels) over the first few hours/days/weeks you play them. Some subs Ive had were quite noticeable, others weren't. Worst Ive ever needed to do was re-adjust my gains and slight EQ'ing. Most people dont even notice probably...