I was gonna post a new thread with almost the exact same question, so if you don't mind I'll watch yours. Maybe we'll both learn something.
It hasn't been two weeks for us, just 4 days. It seems the two little seedlings unfurled their first true leaves, then they've done nothing but grow a little bit leggier. Actually, one hasn't really unfurled its first true leaves - they're still held together, like hands praying.
One A51 XGS panel set to 65W mode, seedlings moved from Jiffy peat pots to taller pots made of some sort of soft cardboard-like material that's supposed to break down, only giving them a dash of pH-adjusted water when the soil dries on top, no nute supplements.