I (not very cleverly from what I've read on here) bought one of those "grow a bonsai" kits from Amazon the other day, it arrived today and since then I've been perusing the internet on advice for care of bonsais. After spending the last several hours reading through just this section of the forum I have realised what I actually have is a hopefully grow a tree if you don't kill it first kit so now I'm in it for the long haul. In a ideal world I would like to have something that I could potentially start working into a bonsai in the next decade or so (if I end up with some alive trees by the end of it I will be happy as well).
The seeds I have bought are for Japanese Black Pine, Wisteria, Japanese Red Maple and Judas tree along with some Pomegranate seeds thrown in for free. I've had some brief and relatively useless experience with acers before but nothing with the others apart from walking past some wisteria climbers. I have grown other general garden plants in that past so have some very basic horticulture skills but this seems to be a whole other ball game and I would like to attempt to get it kind of right. I've followed the instructions in the book for the stratification. Once planted and if anything does germinate then they will be heading outside (apart from possibly the pomegranate as the advice seems to be they like heat) to live on top of the storage box as any lower and they will definitely not survive my dog's gardening attempts. Any advice on young seedlings and surviving frosts would also be appreciated though so far here in the North West of England it is relatively warm for this time of year.
What I'm trying to ask in a very round about way is what do you personally look for in a plant to see if it has any potential as a future bonsai, what age do you generally look for those things and any general advice you have while I continue to use the time that I have to research further into actual bonsais.
I would like to have something in the future but I'm happy to settle for an alive tree that looks half way decent. The booklet they come with suggests that there should be something to start working with in 2-3 years though after reading through here I feel like it will be much much longer before I start doing anything with them other than just keeping them alive.
If all else fails they also threw in some sunflower seeds and I know I can grow them at least.

The advice you are looking for is offered repeatedly on this forum. Have a look at the Search option.

If you want to get into bonsai, you will need to start studying. I do not really see the point of copy/pasting information that is readily available.

Then feel free not to reply. I am aware I will have to study however I believe asking for advice from people who have already done it or are working towards it is a good way to start along with reading books and the internet.
I have tried the search option and didn't get much joy from it so I have been working my way through the threads. In the meantime if you have any advice that would actually be helpful it would be very appreciated. If you don't wish to share then as I said feel free not to reply.

www.bonsaiempire.com/basics/cultivation/from-seeds

What I'm trying to ask in a very round about way is what do you personally look for in a plant to see if it has any potential as a future bonsai

If you are still referring to your seeds, the question makes no sense, as all that they have is potential.
if you're looking to buy a tree:
www.bonsaimary.com/buy-a-bonsai-tree.html

what age do you generally look for those things

The age is not so important, it's the look that counts.

If you are looking for advice: Bonsai is a marathon, not a sprint. Interprete as : you have all the time you want, study/learn/see... first, then do something.

My personal advice ( what i have learned): If you have to ask, you are not ready to do what you are asking.

In your case: seeds are in the ground, so no need to do anything for the next few months. You want to buy a pre-bonsai: no need to do it now, take your time to ask questions, learn, look around. In the long term this learning time will earn you years when it comes to letting trees survive and thrive.

I would recommend pacing the seeds in the soil outside. Wintertime is erfect for stratification and as soon as it warms up outside, the seeds will germinate. At that point the amount of outside light & temperature will help create strong seedslings. Keeping them indoors untill they germinate is not helping their survival chances.

I look for a good Nebari, and lower trunk movement in trees. So when growing your seeds out, this is what you have to ensure. This is relatively easy to control for in your plants.

Thank you for the replies, they are helpful to me. I fully plan on using the time I have to read and learn hence asking questions as I always feel if you don't ask then you don't learn especially when new to something and people are here who've been doing it for a long time so who better to learn from.

I will place them straight outside then to grow although one more question on that point : Would the pomegranate be OK going straight outside or would it be best to waiting to touch those seeds until the spring? The advice in the guide says to put them somewhere hot and suggests on top of the boiler but I feel like that will kill them before they've had a chance.

I realise with the way I wrote the question about potential doesn't read as clear as I thought it did but that is what happens when you write at the wee hours of the morning. It would have probably read clearer if I put what do you personally look for in young plants that makes you think they have potential as bonsai or are just going to be a pretty garden tree. Thank you leatherback for your answer at that point.

I like doing things that go for the long term and have a good learning curve so I'm very happy to settle in for the marathon.