AusBonsai

G’day folks,
Early Christmas present that I’m not entirely how to plan for its development. I would like to develop a bigger trunk but I would also like to get some movement in there as well. I repotted it a month ago.
Should I just leave it alone for a year or 2? Pick a leader and shorten the others? Prune it all?
Any advice would be gratefully received.

Plant in ground in winter after doing a bit of footwork and then leave to grow over a couple years

Thicken the trunk is a matter of time and growth. The longer you leave it the thicker it will get. The more growth on branches the thicker it will get so pruning will remove growth and therefore reduce thickening.
Growth is also related to the amount of space the tree and its roots have. A larger pot will usually allow more growth and therefore faster thickening. Planting in the ground will usually allow fastest growth and therefore fastest thickening.
A big warning though. Fast trunk growth is not always best for bonsai because fast trunk growth can also accelerate problems - larger scars, larger bad roots, etc. Not every trident planted in the ground will end up as a show stopping bonsai, even with plenty of experience.

Trunk movement in deciduous trees is usually made by pruning. Each time you prune a new leader will grow at an angle from the trunk which gives a slight (or larger) bend in the developing trunk. What you see now is nothing like the future tree. Most of the current growth will be pruned off at one stage or another.
Wiring will give bends in a trunk but does nothing for taper. Taper in deciduous is vital for good bonsai and pruning is the best way to achieve that.
Nebari is another important aspect of deciduous bonsai. Visible surface roots show stability and age. It is important to start working on the roots quite early in development.

Even with accelerated growth you should still plan on 4-10 years to get a good bonsai. 2-3 years for trunk growth and another 3-5 years to develop branch ramification. Allow extra years if you want a thicker trunk and extra for inexperience. Take a few years off if you're happy with less quality.

Unfortunately developing bonsai is not an instant thing. Patience is required when starting with young stock. At this stage I think the best thing is to leave it to grow at least for this summer. Give the best care you can to get most growth and then work with the result next winter/spring.

Thanks heaps for the replies. I thought this was the case but couldn’t articulate it the way Neil did.
I feel very inadequate with young trees just starting their development. So this is really good and timely advice.

Everyone starts somewhere. If circumstances dictate starting with younger trees so be it.
I think it is worth while looking out for a tree that could go straight into a bonsai pot with minimal work (or a ready made mallsai). The result may not be a show winner but it will give any beginner a sense of satisfaction and the experience of keeping a tree alive in a smaller pot.
In the meantime look around for trees that need time and work on developing those in the background or save up to invest in better starter trees. As these improve they can supersede the original mallsai.
Over the years you can gradually upgrade to an ever improving collection of bonsai.

Stevie_B wrote: ↑December 10th, 2021, 10:15 am I feel very inadequate with young trees just starting their development. So this is really good and timely advice.

Peter Adam's book on Japanese Maples has lots of info on developing young Japanese and Trident Maples

Bonsai with Japanese Maples
by Peter D. Adams
ISBN 0881928097