Tomatoes & Peppers: First Transplant, 1 by HopeSue

HopeSue wrote:
This is my first season of planting herbs, flowers, and a variety of tomatoes from seed. The flowers (marigolds and zinnias) were planted April 30th, but I was very late in ordering and receiving the tomato seeds, and they were planted around the first week of May. The tomato seedlings are well on to their first set of true leaves, and I have started setting them outside, increasing each day by two hours. Would I be sealing their fate if I were to plant them in the garden in one week, even if I did pot them up?

If I did not pot up the tomatoes, would the risk be losing them to an immature root system? They are still in the Jiffy peat pots in which they were originally planted. Should all seedlings be potted up before planting outside?