When goal-setting is a fixed step, use this clause to mark that moment: When people determine their goals for public speaking, they usually start with the audience. It means deciding what listeners should know, do, or feel. If the step might not happen, if reads clearer.
Writing a course assignment? Use the clause to place goal-setting early in the process: When people determine their goals for public speaking, they often choose between informing and persuading. Here when points to a stage in time, before the drafting starts.
Coaching a nervous beginner? The clause can describe a habit rather than one moment: When people determine their goals for public speaking, they sometimes skip the step entirely and jump straight into drafting. This reads as whenever, an ongoing pattern where the deciding gets left out.
Planning a wedding toast with a friend? Swap in the same clause naturally: When people determine their goals for public speaking, they sometimes realize they'd rather entertain than inform. The clause works in casual talk, not just textbooks.
Testing your own sentence? Ask whether the goal-setting is a fixed stage or a step that might not happen. A fixed stage, like the goal-setting speakers normally do before drafting, calls for when. A step that might not happen calls for if, since the clause then names a condition rather than a time. Once you've settled which reading fits, reword the rest of the sentence so it matches: When people determine their goals for public speaking, they usually pick a clear purpose first. treats goal-setting as an expected stage, while If people determine their goals for public speaking, they'll realize how much it sharpens the speech. treats it as something that may or may not occur.
Is goal-setting a fixed stage every speaker goes through? Then when marks that moment, as a textbook would: When people determine their goals for public speaking, they usually pick a clear purpose first.
Could the step be skipped? Then if fits, as you'd say to a friend who jumps straight into drafting: If people determine their goals for public speaking, their outlines come together faster. The benefit only holds for those who actually do it.
Whatever you choose, keep the goals concrete. The phrase works best when the sentence points to specific, measurable targets rather than a vague wish to improve.
A model that keeps that specificity: When people determine their goals for public speaking, they can aim to speak with fewer flaws within six months. It names a concrete target and a deadline, so the clause reads naturally.