1. Immediately take photos of all the plants laid out so the plant and the labels are clearly visible. This has helped me on more than one occasion when I got a little confused or the little plastic bans with the names slipped off. That will also help to confirm you got the correct number of plants.
2. I like to use separate containers if I am working with more than just a few plants. I like to keep the number down around four. I will put those four plants in a container to soak, then later take them down to the garden (helps a lot to have the holes pre dug and the name plates already in position) and plant those. Then come back for the next batch.