I was recommended to repot these trees into their own small pot before their roots start tangling into one another (I fear they may have already started). "A little wider than a pop can" was the recommended size. So if I SHOULD repot them into their own pot. What advice and tips can you offer me?
Completely new to this, so I will only move some of the them. If it goes good, I will move the rest of them the next week.

I would leave them until early spring, late winter next year and then put them in individual pots.

Once they are big enough to handle then they can be potted up, But they really must be outside.

They are outside.

FrankC wrote:

I would leave them until early spring, late winter next year and then put them in individual pots.

So I take it that I won't have to worry about their roots tangling up in each other? Winter is 6 months away and I read on many sites to repot them into a bigger pot after 3 months. I planted these April 22.

You will find many answers to this question, all the same. Put them in the ground if possible, and outside.
Don't do anything to them until spring. That will be March or so in the northern hemisphere.
Put them in pots a little bigger than the size of the roots, an inch or a couple of centimeters bigger, depending on where you are. Then move them to pots a little larger when the roots get bigger. Water them and fertilize next year. Don't plan on doing anything of a bonsai nature fir many years.

Thanks Ivan, I will wait until spring. I will continue to do what I'm currently doing. Keeping them outside and watering them when soil has dried.
I can not plant them in the ground as they will die; too much rain and the soil here is really bad.

You can repot them now and do a little root work like removing the tap root .These pine seedlings are tough bastards.
Or you can do a seedling stem cutting on a few of them to create a better future root base. I did that 2 years ago. Here's my progression from the start to a few months ago: shumibonsai.wordpress.com/tag/japanese-b...pine-from-seed-2018/

As I said, as soon as they are big enough to handle they can be potted up. As no roots will be cut it is not a problem, the sooner they are able to grow the better.

I appreciate the info guys.