that happens. when i did mobiles, i usually played the more chilled out jjj hottest 100 style shit til after speeches, or til someone comes up and requests a dance song, then you know they are ready to dance. When you drop a request as for first dance track, that person grabs all their friends and gets them to the d-floor, and kind of gives you a kick start. You don't 'waste' floor fillers early when people aren't ready to dance then too. However, also had gigs where nothing I play works, it happens. Just so unpredictable