The best way to treat DW (absent lake renovation or killing the fish) is with a systemic product like Sonar. That is not your situation however. You have no fish and need speed for a short period.

For that you need a contact (fast acting product) like Reward. Also you have a conundrum in that water agitation (waves , vigorous mixing , wind ) will help kill/reduce DW but it will also make the Reward less effective. The other complicating factor is timing. DW has a nasty advantage in that it produces turions ( seeds which fall into the mud and don't come up and start growth until the surface light hits the bottom). DW can double in volume everyday and with the turions active can cover the pond in a few days time. That is why a total water body product like Sonar works better than a contact product as it covers the whole system for a longer time and thus gets the seeds (most of the time, often a second application is needed).

My suggestion. Be ready to do several things in sequence and have a backup plan.

Get some Reward with an adjuvant (Side Kick II or similar which cuts through the waxy covering on DW)). Start now and spray it with a strong dose. That should kill all the DW it contacts. See how long it takes. Once the water clears be ready to spray again. Keep ahead of the stuff by spraying patches as they appear. A few days before the event start up the fountains for surface movement. Hold off on the aerator as it will help long term but for now it will circulate the turions to the surface which you don't want. About 3-4 days before the event be ready to spray the entire pond again if any DW is present or if a film or sludge type stuff is on the water ( a pre-cursor to a new batch of DW popping up). You could try to combine a Reward application (same time but separate application) with Sonar or White Cap or Habitat (systemics).

There are other things that work but I don't think you want to go there as they are not aquatic approved.