Well, not wanting to learn from people who also grow other trees is not a way to necessarily get any help, even if I understand what I think you mean. People who grow bonsai (beyond a gift plant they have for a time) tend to accumulate many, many trees over time, and learn an enormous amount about horticulture in general, and their own trees in particular, but many of the techniques used are the same, even if not always carried out at the same time and in the same way (to allow for differences in the trees). Learning to water bonsai can be a long road, as they are not treated like house plants, and learning about soils and light and many other factors takes some dedication, experience and time, and I would not consider myself a grower now (after decades) if I had been afraid to learn from others. However, your tree is tiny right now (Scheff's can grow to be very large) and will not grow much if left in that pot, so it would be best for it to be not only in a larger pot for now (not necessarily a bonsai pot, though one that's wider vs tall would be good to encourage lateral growth of roots) but also in a proper soil mix - not potting or garden soil, as well as having enough light (there's definitely more to that). Once the tree has developed a woody trunk vs a green stem (at least 2-3 yrs), and more substance all around, then you gradually do two things - one would be to start pruning the roots to a definite pad, a shallow and wide bowl shape, which would fit into a bonsai pot, again not all done in one year, and the second would be to begin pruning branches selectively to develop new smaller ones, and foliage. The root pruning and eventual placement in a bonsai pot will slow growth quite a bit, and the new crop of leaves will only grow so large which, together with the fatter and somewhat taller trunk, will be in proper proportion for a bonsai, something you can't expect to have immediately. Schefflera's are not really traditional bonsai material, but if you know what you're doing and take proper advice, as well as providing the right environment (lots of light, which is often supplemented artificially by the right equipment, lots of humidity - not misting, but with a pebble tray of water that never reaches the pot bottom to rot roots - and watering only when a fair amount of the mix is dry (usually more than less), rather than to a schedule, or e.g. like a houseplant. I wouldn't pinch anything much yet, as while it might provoke a few more leaves now, it will otherwise slow the overall growth, and I'm sure you wouldn't want that. There's a lot of information online, so for basics, go to www.bonsai4me.com, and for tropicals in particular, www.bonsaihunk.us/cultural.html (the best there is). Also look for a club nearby as they're great for seeing how things are done vs trying to interpret terms from reading, and great for getting questions answered.

Carmellia
In addition to Lucy's advice go to Jerry Meislick's website
www.bonsaihunk.us/info/schefflerabonsi.
He also has a book about ficus but would probably be great info. for any "indoor" Bonsai.
Good Luck

OOPs Sorry Did'nt realize Lucy had mentioned Meislick.