I'd start it now re the 4" sandbed, with flow, and the rock rubble, add the cheato and turn on the light the day the cleaning crew goes in and never turn the light off.
Reasoning: right now you want its sandbed live and functioning, not cycling later.
And the phosphate seemingly won't be too available until after the cycle is done, according to some of my correspondents---at which point it will start entering the water and the algae will take off in a hospitable environment. You just want to make your fuge 'hungrier'. So as your cleaning crew goes to work and poos that phosphate back into the water, your fuge will be ready to grab it.