Yes; "when," when used as a relative adverb, will describe the previous noun, just as "who," "which," or "that." It should be used only to describe a time, such as:
"I cannot remember a time when you were not by my side."
Keep in mind, though, that "when" is more often used to introduce an adverbial phrase modifying the main verb of the sentence:
"When the clock struck 12, Cinderella's carriage turned back into a pumpkin."
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