Avoid the forced-sale trap
A car that needs to sell this week is marketed differently from a car that can wait several weeks. Neither approach is wrong; the problem is acting as if the deadline does not exist. Be clear about your date and your minimum practical outcome from the beginning.
An assisted sale can be useful because the owner does not necessarily have to surrender the vehicle while it is advertised. You may keep driving it while serious interest is handled, provided viewings and handover can be coordinated around your schedule.