First Grow. Indoor/Sunlight

Not exactly sure of the strain, I just know the seeds came from either Sour Diesel or Blue Dream.
I had about 10 seeds from last summer and threw them on a damp paper towel. 8/10 popped, but I chose 3 that seemed like they would have a stronger root system in the long run.
It's been roughly a week and a half since they've hit dirt. I used the bases of some 20oz soda bottles and plan on keeping them in those throughout the duration of the grow as I'm in a small apartment and wanted to get the hang of things before jumping into a big investment.
So far I've watered them twice. Today I came across some white, wispy growth on top of the soil, which I've scraped off and layered over with more soil. I chalk that up to too much moisture.
I haven't been doing anything other than leaving them in the window sill.
One was a late bloomer popping out and seems to be struggling though I've done nothing different to it than the other two.

The 3rd single photo is the late bloomer and the one the seems to be struggling. I'm no expert though so any input and/or advice would be appreciated. Thanks!

nice. You can add more soil around the stretchy stems if you want. I normally start out with room to add soil for just that reason. If they look pretty stable I let 'em go for a while.

can't wait to see them progress.

Well, a quick update.
Had to toss one of the plants. Currently waiting to see wjat comes of the strongest one (the first picture in OP) necause I was replanting them and my cat pounced it (snapped the stem towards the bottom, but it's still attached, replanted with the break beneath the soil)
Hoping that it will sort itself out.
The runt is growing stronger (last single picture in OP)

Another update. Everything seems to be going well. The first plant with the snapped stem seems to have recovered and is back to growing. The runt is growing taller, still being a runt. I'm not sure what to make of it, but I'm going to let it keep growing since it wants to.

First image is the plant that had the snapped stem. It's been 9 days since I replanted it deeper in the soil.
Second image is the runt. No idea what's wrong with it.