I used to worry and worry over getting this timing correct. I can only share what I have come to and see if there is something there that helps.

It's long so hang on for the ride.

I decided that I wanted to teach my children first about the Bible and God and second I would let History fall into that. I would get one good cycle at least of History and then other than that I would give them lots of books to read that covers it even farther in depth. PS kids don't get multiple rotations of the history cycle. In fact the biggest focus in elementary is American. They would get one rotation and it would be no where as in depth as what they get in a hs environment. The rest of the focus would be on government. So knowing that my first call is to Him but also wanting them to be well equipped for any call He might give to them individually, I have learned to make the curriculum my tool rather than being a slave to the History cycle or a slave to the vision of the writer. Luckily here I find Carrie is extremely like minded to my vision in the first place and that really allows me to use HOD as the perfect tool for us and still accomplish my big goal of God first in equipping them to whatever the call.
That being said I do not think the rest of the world values History cycles the way we seem to in the hsing community. If you look at an SAT what is on it. Do you even find History really? This is what the SAT covers
1. Essay
2. Writing
3. Mathematics
4. Reading
5. Equating (the one that doesn't count toward your score)
6. Mathematics (includes SPR questions)
7. Reading (includes 2 long passages)
8. Mathematics
9. Reading
10. Writing
This is the basic and standard SAT test that is what most people end up taking for college entrance. History is only offered only as a subject test that is an additional SAT test.

Most colleges do not require subject tests, those that due usually allow the child to pick the subject and if you picked History I would hope it is because you are going into politics or plan on being a Historian. I can't in all honesty looking at the subject test believe that if a college picked the subject for the child that History would be the subject picked but if so I think a little SAT prep (which we plan to do anyway) would bring to mind what we learned and teach them how they need to know it to score high on the test. My view is if my child is called to either one they will acquire enough extra knowledge in their own reading to ace the extra review that might be needed in that area or else it will be made clear to us in hs and we can then add extra course work in that area.
That is the "logical" to the world and logical for college. The illogical to the world is actually what I hold higher.

Our plan is to have a minimum of 4 tours of the Bible before they graduate and study that deeply. I figure all of their life experience and future success rests more on us accomplish that than anything else we could do in the way of History. I do think it is important to understand History in the context of knowing God's hand in it and seeing how He brought us or in some cases how we got her because we turned against Him. But when I look at what probably will get them into a good college and allow them to have whatever call they want Bible is first in my mind and then LA, Math and Science would be what comes second in my mind along with teaching them life skills along the way. And then after all that I think a firm grasp of the History cycle is what would come next. In all logical thinking about what the SAT asks as well as what they are probably going to look at in college admission (knowing also that 7-8th grade course work can be added to a transcript for highschool to show that subjects were covered and it is perfectly acceptable apparently to do that under additional course work and not even have to put the "grade level", you can even list specific books read or programs used, there are books that show you how to prepare transcripts this way for homeschoolers)and then looking at probable careers and thinking what would be the requirements for those also knowing that college will provide anything necessary for that we have missed, I am thinking this works.

So our focus is on one solid tour of history and if it all does not fall in high school I am fine. Certainly our Bible will count as some of that but also enough outside reading could cover anything we find we have missed. My kids read some of the books from BF just for fun and I try to keep our book shelves stocked with plenty of fine reading, history and science. I find they really do learn quite a bit on their own and there if I put enough of that together and add a few essays and tests I have really a course in a pinch if I need it. As long as they know the information in an acceptable and above average way then I do not care how they get the information.
I just want to give you a different perspective. I know it does not match the popular thinking in the hs environment and it may not match at all what you want or are called to do for your kids. But I just want to encourage you to do the reality check on what actually is required and if more history is required it would not be inconceivable to be taking two different history courses in high school as long as you do not make them both unit studies and if you had to do that it would actually reflect what college will bring anyway. I had a few years of nothing but science in my college experience so I am thinking if later on they end up needing for their call or college entrance two of anything other than Math or science that has prerequisites why not give them a taste of the real world along the way.
I hope there is something that helps you here.

It is obviously something that I have thought about a lot. If nothing helps you here at least maybe you can see someone who is wackier in figuring out how to deal with the subject of history cycle than you.

But in all honesty I know how crazy making this all can be. I pray that you find a solution perfect for your family that gives you peace. I help there is something here that helps you.