Answer: If the leggy plants have 3 sets of leaves you can pinch out the tip of each plant and it should branch where the lower sets of leaves emerge from the stem. If the seedlings have fewer than 3 sets of leaves, don't pinch them yet - wait for more leaves to develop. If the plants are flopping over at this point, you may want to discard them and start all over. You're right - the spindly plants are reaching for the light. If they are simply leggy and not flopping over, they may still be okay once they mature for a few more weeks. Provide light for 14-16 hours a day and they should be happy.
Best wishes with your plants.
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