An evaluation is generally a check that education is happening, not an inspection of whether you are doing it well. Evaluators are usually experienced homeschoolers or teachers, and most of them want the meeting to go fine.
The preparation that helps is assembling evidence that something coherent happened across the year, which is a smaller job than most people fear, particularly if anything at all was recorded as you went.
What to bring
6 things to do
Ticks are for this visit only. Nothing here is saved anywhere.
Progress is what they are looking for
The single most persuasive thing in any portfolio is the same subject at two points in the year. October and March writing samples side by side say more than any quantity of finished work from one week.
It is also the easiest thing to provide, and the thing most people accidentally leave out by only keeping the pieces they were proud of.
Be honest about what did not go well
Saying that maths was difficult until January, that you changed curriculum, and that it improved afterwards is a stronger position than implying everything went smoothly.
It demonstrates that you were paying attention and adjusting, which is exactly what an evaluator wants to see. A portfolio with no difficulties in it reads as curated rather than complete.
If you are behind on records
Reconstruct honestly, mark approximate dates as approximate, and do not invent precision. A clearly reconstructed term is a normal thing to hand over.
The full recovery method is in when you have kept nothing since October.
Check what your state actually requires
Requirements differ enormously, and preparing for a stricter standard than yours wastes a weekend. The state-by-state position is in record keeping requirements by state.