Instructors usually teach the same way that they fly. But they should let you fly with what you feel comfortable with. I myself use the thumbs only, but I have had 2 students that preferred 2 fingers so I let them fly that way. Just ask them to let you fly with what you feel comfortable with. But..... (isn't there always a but????) only as long as it doesn't interfer with your training. If you are having trouble finding neutral, or any other problems, let them train you their way. If it's not causing problems with your flying then use 2 fingers

Hope this helps

Ken