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.
This can also help you stay comfortable while you're exercising. Alternatively, you can simply avoid breast-feeding your baby right after your workout. After months four to five of breast-feeding, physical activity has less of an impact on your milk because your body produces most milk at feeding time.