As I recall the Waterloo swap takes July off. My daughter and I try to go a couple times year and try to get there between 8 and 9 am as most "vendors" start packing up about 12noon.
Annette
2 EE, 2 Polish, 3 RIR, 1 Black Tailed Jap, 1 Golden Seabright, 1 Buff Brahma, 1 Millie Fluer