Your putting it into your long-term memory bank during the first day. By studying or reviewing dream related material all day will force it to be stored in long term.

By then recalling it a few days later your bringing it back to active memory. This technique is pretty much MILD. Your storing the information for later use. Then, you call it back into conscious memory before bed hence causing it to linger in your thoughts. As you fall asleep this thought is more prevalent than other unconscious ones. So it will be more likely to remain on your mind and in conscious memory as you fall asleep bringing forth the greater possibility of a lucid dream

However, this can fail because its very easy for other thoughts to be brought forth, forcing lucid dreaming thoughts out of the active memory bank and back to the unconscious.