I always vary feeding time a bit. It is a trick I learned after the first show with my horse... He was not a happy camper when one of his classes delayed dinner time. Being less rigid with the time and more rigid with a routine has made the time change a non-issue (though the horses have not had to learn to sit, they do have to wait for me to give the 'eat' signal before they get their grain like my b's have to wait for their 'eat' command).