Start with the working day
The first thing to get right is the daily picture. If the owner, the front desk and the technicians all see the same list of jobs, most of the phone calls between them disappear.
Everything else, from reporting to records to history, is easier once the day is accurate.
Then follow the money through the job
Work priced on an estimate should be the same work that gets invoiced. When those live in different tools, margin quietly leaks through jobs that were extended verbally and never re-priced.
Rolling it out without stopping work
Do not migrate everything at once. Run new jobs through the system from an agreed date and let older work finish the way it started.
Agree who owns the daily view. Someone has to keep it honest for the first fortnight until it becomes the habit.