If your 11 yo is new to doing dictation, I'd begin with Level 3. If it seems super easy, I'd fast forward to the middle of Level 3. If that seems super easy, I'd try to start Level 4. I think it is key to read over the dictation process described in the Appendix, as the way we go about this as teachers can effect how dictation goes so much. We feel a good pace for dictation has been established when our dc are missing 1 or possibly 2 passages a week. If a child has to retake a dictation 3 times or more quite consistently, I think that is an indication that it is too difficult and the child should then back up and do an easier level. My oldest has maintained this pace (missing about 1 passage a week) through Levels 2 and 3 and a third of Level 4. But, it was about there that he started missing more passages in a row. He reached a level he had to study more for, and he was not taking the time to do it. I let him study "his way" for a few weeks, and then asked him to study "my way".

This seems to go better, because there's always a chance his way will work. However, this time it didn't. So, I asked him to get a marker board and read the passage out loud, writing down any words that were more difficult to spell, and writing the punctuation marks along with the word proceeding them as they occurred in the passage as he was reading it out loud. So, studying this way looks like this:
Martha
kitchen
do.
mother,
table,
pineapple.
Here was the passage he studied:
Martha went to the kitchen to see what she could do. Her mother, who stood near the table, asked her to put the oranges and melons on the shelf near the pineapple.
He hasn't missed a passage since he has studied this way. In fact, he laughed and said pretty sheepishly after a few weeks, "I hate to say this mom, but your way really does work better." Once in awhile, I'm right!
I share this just in case there is a bump in the road with studying. I think it's a good idea to first let dc study the passage on their own and see how they do. They will come up with their own strategies for studying and as long as it's not writing the whole passage first and then doing it again for dictation, I'd guess many different strategies could be used based on dc's preferred study methods. But, if your dc hit a rough patch when you get going, I thought I'd share this tip since it's helped out my ds.
In Christ,
Julie