1. Explain it simply
从 (from) goes directly before the starting point, whether it is a place, a time, or an age.
It often pairs with 到 (to), which goes directly before the end point: 从 A 到 B.
从 also pairs with 开始 (begin) to mean 'starting from': 从八岁开始 = starting from age eight.
Never put 从 or 到 at the end of the sentence, and never swap the start and end points.
2. Show examples
从我家到公司很远。
Cóng wǒ jiā dào gōngsī hěn yuǎn.
From my home to the company is very far.
place to place
从八点到十二点，我都在学校。
Cóng bā diǎn dào shí'èr diǎn, wǒ dōu zài xuéxiào.
From eight to twelve I'm all at school.
time to time
他从八岁开始学跳舞。
Tā cóng bā suì kāishǐ xué tiàowǔ.
He started learning to dance at eight years old.
从……开始
3. Share a tip
Keep 从 right before the start point and 到 right before the end point: 从 A 到 B. To say 'starting from', use 从 with 开始 instead of 到.