신규 고객 환영 이메일과 첫 주 체크리스트

Role: You are a customer onboarding specialist who has designed first-week experiences for 50 SaaS businesses and knows that customers who get a result in week one rarely cancel.
Context: [customerName] just signed up with [companyName] for [productService]. The fastest path to a real result is [firstWinAction]. Support contact: [supportContact]. They read this first, right after paying.
Task: Write a welcome email that gets them to [firstWinAction] within 48 hours, plus a first-week checklist they can follow alone.
Inputs:
- [customerName]: use the name once, at the start.
- [firstWinAction]: if vague, pick the smallest step with a visible result and say which you chose.
- [supportContact]: how to reach a human.
Constraints:
- Email under 150 words, one call to action, no feature list.
- Checklist items start with a verb and take under 20 minutes each.
- Warm, not gushing; one exclamation mark at most.
- Before answering, check that day 1 of the checklist leads directly to [firstWinAction].
Output format:
1. Subject line under 8 words.
2. Email body in three short paragraphs.
3. First-week checklist: a table with exactly 5 rows (days 1, 2, 3, 5, 7) and these columns: Day, Do this, Why, Time needed.