I've tweeted them to get an idea of how many people are coming.
I've printed out the info packs and they have a PDF with their rough timetable and suggested places to go, e.g. 5.30pm start/intro/meet up and group up, sunset at 9.21pm (with places that might suit a sunset shot), after sunset (including advice "not to photo the sex workers in Soho - just don't", which amused me), 4am then 8am onwards.
I've uploaded that particular attachment here -