Soaking seeds before planting is an old time gardeners trick that many new gardeners are not aware of. When you soak seeds before planting, you can significantly decrease the amount of time it takes for a seed to germinate. A seed is relatively pampered. Soaking seeds before planting helps you to break down the seeds natural defenses against what it expects from Mother Nature, which then allows it to germinate faster.
For most seeds, moisture levels play a big role in alerting a seed to optimal grow times. By soaking the seeds, you can quickly boost the moisture content around the seeds, which signals to the seed that it is now safe to grow.
And lastly, for some types of seeds, they actually contain germination inhibitors that are designed to prevent a seed from germinating inside the fruit. These inhibitors must be leached away before a seed can germinate. In nature with natural rainfall, this process can take some time. But, when you soak your seeds, this process is sped up.