Hey Ben, awesome to see you are getting into it – keep it up!
Horses are by far the best when it comes to turning bonuses over. We get 80-100% on a consistent basis in the Elites.
ATM sport is a bit dry. Have a look at this forum here
best bet with sport would be checking from Thursday-Friday onward regularly. It is normal to check once and not find anything around. Just have to have some patience and consistency.