Clipping a foal's coat really depends on the climate that the foal is living in, in my opinion. By the time an owner puts their foal up for sale with a clip-job, more often than not, it is summer time. It's also the time that many owners will start taking weanlings to shows. WHEN the foal is clipped will not affect the coat in regard to its quality or color when it reaches maturity.
Trimming a foal's hooves....We've done them as young as one week old because they needed it! (Usually newborns need it at two weeks.) Normally, a two week old foal only needs to be rasped at first, but we tackle their hooves as they grow and when needed, not on any specific "schedule".....unlike a mature horse. This often means they need trimming more often than an adult throughout their first year.
MA