The date of each event is now set by the Kentucky Derby, which is always held on the first Saturday in May. The Preakness Stakes is currently held two weeks later; and the Belmont Stakes is held three weeks after the Preakness (five weeks after the Derby). The earliest possible date for the Derby is May 1, and the latest is May 7; the earliest possible date for the Belmont is thus June 5, and the latest is June 11.
No. Exercise contributes to your overall health and is beneficial and appropriate for breastfeeding moms like you. Even vigorous exercise does not significantly affect the amount or composition of milk your body produces. And despite what you may have heard, it's unlikely that your baby will reject your milk even if you breastfeed shortly after exercising.
Breastfeeding can and should continue when menstruation resumes. Mothers sometimes notice that their babies become fussy at the start of menstruation, perhaps because many mothers have a slight, temporary drop in milk supply at the start of their period. After a few days of increased nursing, the supply will return.