empty nesters... if these walls could talk

Often when a child leaves home, the parents have already downsized a bit, especially if other children have moved out prior to this. Possibly,  the best strategy,  is for parents to discuss how best to utilize the vacant room and to plan and prepare ahead of time; some may wish to wait a few months, just in case the child unexpectedly returns. Others may decide to box and store the child's possessions and move on from this point.

One other consideration involves the reason for the move-out itself: if a child is going off to college, he likely will not return for at least a semester; it may be wise to wait until that time has passed. If the child is moving into his "own" place, and is financially and emotionally prepared, it may be less likely that he return.

It really comes down to a simple matter of preferences and accounting for emotions and practicality. Parents know the child, the situation, and have their own lives as well - it's not all about the child, after all.