The precaution about using wave models for swell prediction is doubly important. It's a model that uses a model to make a prediction. That is, the wave model uses an atmospheric model to determine the future state of the atmosphere, then makes a prediction of how the atmosphere will affect the water under it. So there's lot's of room for error. Wave models do not perform well for smaller weather systems or systems where a high pressure gradient is present.
Hurricanes are a good example.
It seems the atmospheric models have difficulty accurately predicting the wind speeds in high gradient scenarios, which in-turn rapidly diminishes the wave models ability to accurately predict the sea heights the wind will produce. Rather, for hurricanes, surf forecasters develop their own rules based on experience and practice. And with the advent of the Wavewatch III wave model and it's Swell Period forecasts, the error factor starts rapidly compounding. Generally, Swell Period is a function of the height of the sea that produced it. This will result in the swell arriving earlier than what is forecast.