Seedling appeared a day or so after planting. However, it hasn’t shown any growth for about a week. Is there reason for concern?
Welcome ! Seedling is developing underground roots before you see much foliage. I would say you’re going to be fine.
Pics, watering practices, and a few comments on the environment would be helpful.
Young plants will sometimes pause visible growth while they lay down roots.
Here is mine after a week and 2days
They just do that, as said above, probably just laying down roots
Wait for it. However I would have filled that cup up to the top with soil, roots will fill that cup before you are ready to transplant even when full of soil. If there is not enough room for roots growth will slow or stop all together.