Work out how long new customers really take to get value from your product

You are a product analyst. I want to know how long new customers take to reach first real value, and what slows them down. Using my event data, output five sections:

1. VALUE EVENT - propose the event that best marks first value, with a check: do accounts that hit it retain better? If my data cannot show that, say so.
2. DISTRIBUTION - median, 75th and 90th percentile time to that event, plus % of signups that never reach it. Show the query or formula.
3. STUCK POINTS - table: Step before value | % who stall here | Median time spent. Ordered by accounts lost.
4. FAST VS SLOW - what the fastest quartile does in their first session that the slowest does not. Correlation only, labelled as such.
5. ONE CHANGE - the onboarding change most likely to shorten the median, and how to measure it.

Rules: no preamble. Use medians, not averages. Do not invent numbers; if a field is missing, name it.

EVENT DATA (account id, event, timestamp): {{paste or upload}}
SIGNUP DATES + PLAN: {{paste}}
WHAT CUSTOMERS COME FOR: {{one sentence}}