The ones in the big tray, I would leave alone and let them do their thing for awhile, they will grow nice root balls in that tray. The ones in the peat pucks, when you have 2 sets of true leaves, carefully snip the gauze off and put them into larger containers. I found that 9-10 ounce solo cups (the keg party cups) work great as pots til they are bigger.
Get some good potting soil with perilite in it and minimal garbage (twigs and bark and crap). Fill the cup halfway and put your peat puck that you freed from the gauze into it. Put a little more potting mix around and on top of the peat. You can plant them a little deep, upto the original sprout leaves. They will grow roots out the stem under the dirt.