Hello Owiso,
Welcome to the forum! You have two options here.
1. You can test the EAs that Petko provides and you can select the EAs that perform well with your broker.
2. You can optimize the EAs with EA Studio according to your historical data. This brings the risk of over-optimization.
Actually, the best is to generate your own Expert Advisors with EA Studio, following the steps from Petko.
Regarding the testing, it is up to you how long to test the EAs…. I wait for 10 trades and 150 pips profit.