Question

the bold word is a \front swabi\ (subordinating conjunction). does the highlighted comma belong?
when raphael has some free time, i want him to teach me to juggle.
keep the comma
remove the comma

Explanation:

When a subordinating conjunction (SWABI like "When") starts a sentence, introducing a dependent clause before an independent clause, a comma is required to separate the two clauses.

Answer:

Keep the Comma