I have five boys born within a span of 10 years. My first three boys were born within less than three years. So I have had to wash alot of jeans. At one point, I have hung 30+ jeans on the clothesline. That is a lot of jeans.
Fit the patch inside the leg and pin it, making sure that the hole is completely covered. Pin it well, so it doesn't shift.
I hope this works for you. Any questions, just ask.