Found some repotting videos and notes online and carefully loosened up the soil and transplanted the sapling from the cactus pot to a small bonsai pot I had spare, using the extra bonsai soil I have from the Picea. Also trimmed the roots by about a third.
Providing it survives ... wondering if anyone can confirm the species of Maple? Little confused as the sapling has jaggered leaves as expected but then also has two small, smooth edged, oval leaves with obtuse tips slightly olive drab in colour as opposed to the other leaves which are bright green?

Can take more pictures, of either the Maple I beleive it's come from or closer shots of the sapling if it helps. Any feedback muchly appreciated, along with helpful hints to keep it going?!
- Daniel
Solved
By kcpoole - Trident Maple Acer buergerianum