Answer:
Prepare to go on stage once I tell you when the best time is.
Step-by-step explanation:
A group of words when used to modify or qualify the meaning of the phrase or the word is referred as adverb clause.
Adverb clause consists of subordinate conjunctions like as, whenever, when and so forth. Lastly adverb clause answers the 4 W’s that are: When, Where, Why and hoW?