A super bright child is exactly what you have been blessed with. And a "box-checking mama" may not mix so well with a super bright child.
Stop right now and FORGET about the year that lays behind you.
I have 4 kids in 3 guides as well as DITHOR. They have spelling on 3 levels and math on 4.
One of my children has special medical needs and one has special learning needs.
Between the 2, we run to Dr and therapy appointments all week long!
So I have adopted the attitude of picking up on Tuesday where we left of on Monday and not worrying about "where we are" in the guide.
I actually have a checklist spreadsheet of each subject/child that needs to be covered. When I have done the left side of Preparing (for example), I check that off. When I have done Math with Cassie, I check that off. When I have done spelling with Will, I check that off. The next day, whatever is not checked off gets tackled first.
And I would go at his pace with grammar and everything else, not worrying about where the guide says he should be. That's the joy of homeschooling!
The only really great decision I've made for my ds this school year is switching him to a different math. He's using Teaching Textbooks Math 3 now and it feels like a perfect fit for him- he loves it (well, as much as he could love any math lol). Will it be the end of world to go ahead and order Bigger and start it now? Maybe stretch it out to use for the rest of this school year and all of third grade? One other issue is that we added in R&S 2 to Beyond's LA to make it more challenging and already went through about half of the book. Would it be better to keep on with R&S2 at our own pace, ignoring the lesson plan in the guide, and move on to R&S 3 when we are ready- OR just use the guide as written and have a lot of review in LA? I really want to be able to just follow the guide and not do any tweaking but also don't want him bored and complaining about doing school. Some other background info about him to help figure out where he's at......he's working on learning cursive, his manuscript is amazing and almost looks printed by a computer, he is a geography whiz and pretty much knows where every.single.country on Earth is located, is a great speller because he has a photographic memory, and is reading middle school level books in his free time. He has a very challenging personality and doesn't like to be told what to do 
. Maybe that just goes along with being really smart? I'm praying daily for the strength to be able to continue teaching him! Please help with any suggestions you may have! 