Welcome to the HOD Board, Titus2012!

You already received solid advice, and I think you have arrived at a wonderful placement for your dc!

I applaud you for following the Holy Sprit's leading - always the best decision.
In response to a few things you mentioned in this last part of your post - HOD is right on board with you with reading, writing, and math being very important. You will see this addressed very nicely in Bigger Hearts. For reading instruction, HOD's award-winning "Drawn into the Heart of Reading" (DITHOR) is scheduled daily in the Bigger Heart's plans. Be sure you get the proper different reading levels of books for each of your dc, and your younger ds can do Level 2/3, with your older dd doing either Level 2/3 or 4/5 for her Student Book. The level of reading of the book package need not match the level of the Student Book. So, if you feel it would be beneficial to establish a base to build upon in knowledge of story elements (i.e. plot, setting, theme, etc.) and genre study for your older dd and have her do less writing at the onset of DITHOR, then choosing Student Book 2/3 and higher level reading books would be a good match. Or, on the other hand, if you feel your dd is ready for more and has had some reading instruction in these areas already, then she can start with Student Book 4/5. For your ds, he would for sure do the 2/3 Student Book and book package.
You will see many excellent LA skills worked into the plans. Spelling/Dictation, copywork, oral narration, poetry study, and R & S English are included in the Bigger Hearts plans. These LA skills produce strong students over the years of steady practice. They have helped take each of my dc's weaker LA skill areas and build them strong through the years, to create well-balanced, competent students. So, each part of the BHFHG's plans works together in a balanced way to help students build important skills steadily.
For your older dd, I would add the BHFHG's extensions. She is a good reader, and the extensions will fit her well. Also, the follow-up skills she will rotate through each week that are mentioned at the onset of the extension package in the Appendix of BHFHG will extend her LA skills very nicely for her age as well.

Not to mention - the books are awesome!

This will also extend the areas of history and science to be age appropriate for dd.
With these considerations, as well as continuation of appropriate levels of English and Math, this placement is definitely strong enough academically for your dc to enter into public school at any point. That being said - if I may be so bold to say that in my heart of hearts I hope you stay the course with homeschooling with HOD, especially through those middle school years. HOD is partnering with me through these tougher parenting years of teenage ages, and helping my ds and I to be so close with one another! I know this is a rare gift, and I credit it first to the Lord, and second to HOD for giving me the tools - academically and spiritually - to help my ds navigate these years with a strong faith in the Lord.

Praise God - I want that for you and your dd too!
Last, in answer to your question about how do you do this year starting in January - I'd do a day of school every day Mon. through Fri. that you are able, and when summer comes or when a break comes you normally would take - take it. Then, pick up with the next day of plans when you resume. A good rule of thumb is to complete 1 HOD guide within every year. It is important not to double up, or cram in, as the workload becomes too much, and the beauty of the guides being written in a deep way to be savored and remembered is lost. My middle ds is and will be on this schedule. We start a new guide every January. We take our summer off, and we pick up where we left off, finishing that guide by Dec.

This has worked beautifully for him, and I think it will for your kiddos too.

Once you reach PHFHG, the guides from PHFHG on up are 4 day a week guides. If you wanted, you could do PHFHG, CTC, RTR, RevtoRev 5 days a week and you would then, by MTMM, be on board to start MTMM in Sept. and end it in May. However, keep in mind, HOD has taken 5 days' worth of plans and put then in 4 days in these guides to give you a 5th day off. I am not sure if it is worth all that to get to starting in Sept. and ending in May - but it is certainly a workable possibility if you would enjoy that.

You will find many, many, many families are choosing the pacing of 'whenever you finish an HOD guide, begin the next one.'

So, your placement of starting in Jan. and ending in Dec. is completely 'normal.'
HTH, and I look forward to getting to know you here! This board is full of gracious, helpful, Christian ladies - you will fit right in!
In Christ,
Julie