Katherine,
I'm a little confused on your question. The MFW program you are talking about sounds like Rome to the Reformation. That is more designed when the child is ready for a longer school day (such as 3-4 hours to cover 10 subjects). It is a multi level program for being able to be used by families with several children grades 2-8 who are in that time frame with their history study.
I have to say I don't really think MFW's RTR is the right fit right now because of the AGE of your oldest child. It's not really about the "grade level" of reading and writing, but the age of the child who is the oldest in the family.
You might consider holding off a bit in the chronological cycle and consider using either Adventures in MFW or MFW's ECC program. I know that's not exactly what you want to hear, but I do want to be honest about it.
MFW offers good stuff. I've loved it for 5 years. But that program, Rome to the Reformation is designed for a little bit older (i.e. logic stage). Even if your child is advanced in academics, they are still only the physical age that they are. If you are interested in MFW's program, I suggest you at least look at ECC or even at ADV. The Biblical integration is great!
MFW does the chronological history cycle a little differently than other things out there.
K, 1st, and Adventures -- make a mini cycle that is age appropriate.
Then the 5 year cycle ECC, CTG, RTR, EX1850, 1850-MOD cover cultures and 4 years of chronological history at a more advanced level.
Then they have a separate high school program for the rhetoric stage.
So how about taking a big jump in history from ancients, and start in about the year 1000 AD with the Adventures program? It might seem a little light for your high achieving 6 year old, but there really is no rush at this age in all of this.:)
-crystal