One rule off rough framing. Bigger is better. It's easier to add then subtract.

Eg: When I frame a door opening for say a 30 inch x 80 inch door the RSO (rough stud opening) is 2 1/2 wider and 2 1/2 inches higher. This gives you room to shim your door jambs perfect.

The number one fails I see of DIY is trying to frame RSO tight. Not how it's done.

Now bi folds can be a little tricky. Follow the instructions for your finished opening but the concept is the same