Welcome, Amanda! I did not begin using HOD until my oldest was in 5th grade - so wish I had found it earlier in our homeschool journey. He is now finishing 8th grade & our family could not be more blessed.
So, now about your question. If you begin Little Hearts for His Glory for kindergarten, then you could potentially complete the HOD cycle your child's junior year. This, some place, was addressed on the board. Personally, I would hesitate to expect finishing early, only because there are times in our children's schooling (whether because they are really struggling or because life happens - a move, a new baby, an illness, etc) that slowing down to half-pace may be necessary.
![Very Happy :D](./images/smilies/icon_biggrin.gif)
If your child happens to finish early, you could take that year to develop areas of special interest, complete CLEP testing, take college courses etc. I am sure that many women have more insight than I do, but this is just what I remember from a previous discussion of this board.
HTH!