Ok! I'm glad I can weigh in here. Let them grow out is my advice. On my current grow I had four plants, three of which were growing totally normally. Within 3 weeks they had 5-6 nodes and were ready for topping. But one seedling stayed exactly at the stage you're talking about -- still working on the first set of three-leaves. And stay there for something like two weeks without budging. I grow in hydro, and it wasn't really growing lots of short roots. It was growing ONE long root. Just one. It was freaky.
I was going to toss it, but thought it would be a good experiment to leave it alone to see what happened. After a while, the growth picked up, and it started shooting up. Long story short, two of my other three turned out to be male, and between the two females, the one that was stuck as a seedling is by FAR the bigger producer now. It's got the biggest, densest buds I've grown to date. Meanwhile, the other "healthy" female has nice buds, but they're a little small and unimpressive by comparison.
If you have the room, I say grow them out.