You can remember the meaning of 从此 with this easy mnemonic:
A treasure hunter made his way into the maze and reached the magical boxes believing he would be rich from now on. The boxes had powers and minds of their own since (从) their creation, and this (此) day they posed tricky questions to the hunter.
Using mnemonics to remember the meaning of Chinese characters like can have an enormous impact on how long to learn Mandarin it takes.