There are good bonsai, and there are fast-created bonsai. The two don't combine. Bonsai is a marathon sport, not a sprint. If you are unwilling to wait for nature to take it course, maybe Bonsai is not for you, or you have to accept that you will not grow good bonsai..
Consider buying one or two good trunks, which you can use to build your first bonsai, while these fatten up. Tree heigh css trunk thickness (diameter) should be in the order of 6:1 to 12:1, to give you and idea.