Required Data Science & Analytics,Data Mining & Management freelancer for SQL query examples in Google Big query to query App analytics job

I'm looking for a set of example SQL queries in Google BigQuery, so we can pull in data from App users/usage.
All events users generate (screenviews, events,...)
- We define which fields have to be combined, grouped & sorted
- Queries have to be documented
- Queries should be optimised to reduce the amount of data used in BigQuery

Query example
the % of successful onboardings and the average completion time
> COUNT user ID WITH event X, Y and Z in succession AND calculate time difference from event X to Z sort by date

Skills & Expertise Required

Data Science & Analytics Data Mining & Management