I recommend ... the sooner the better!
We own a 2009 Hunter 27 Edge. In previous years, our home port was a fair distance from home so, by the time we spent the day taking down our sails & mast and hauling her out of the water, by the time we returned home we were usually too tired from a long day to clean off the hull. Usually this meant pressure washing a few days later. This is a BIG mistake. In that short time, the dirt on the hull had time to harden enough that pressure washing was made hard enough to cause damage to our bottom paint.
This year we changed ports to a location close to home. Again I put down the sails and mast in an afternoon but I persevered and also completed my hull wash the same day. There is no comparison in the difference this makes. The grime came right off and, frankly, I think our boat was thankful for the immediate wash. With the dirt coming off so easily, there was no damage to bottom paint and I completed the task in probably a third of the time it would have taken otherwise.
Just my two cents worth ....
PLC