Answer: YES
Step-by-step explanation:
Assuming you are talking about the 6th grade article I just found online, technically, yes you can. We live in America (or I assume you are) and do not use originally English. If you lived in the 18th century, and replaced the once with the when, then people would think you're a peasant or something, but you're fine. The word once in these sentences conveys the same meaning as when in modern English. Of course, I can't insure that your teacher won't think you're a peasant, because they're still living in the 17th century. :)