Starting work as a Flat Rate Tech this week

I think the best advice for flat rate work is.

First you learn, then you earn.

You aren't going to be able to compete with the guys that have been there longer. At first you'll take 4 hours to do a 2 hour job, but thats ok because at first they're looking for you to be able to do the job right. After you get your feet wet and they're confident you aren't putting out shoddy work, they'll expect you to get faster. Right now don't even worry about rushing anything. Just go at your pace and make sure you don't leave any parts off or forget any crucial steps. Stressing yourself out over speed can be dangerous for the customers.

In the future be careful for rate changes. Your company will most likely roll out some new way to do things or a new diagnostic tool. They'll claim that you will be able to get the job done faster and make more money. That way they'll lower what was once a 4 hour job down to a 3.2. It'll still take you the same amount of time to do, you'll just get paid less for it. At that time when you are more comfortable with your skills, it'll be time to look for a new job.