As linlaoboo and I both alluded to [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=26870]here[/url] and [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=26913]here[/url] , there is no need for specialized soil to start seeds. Anything that drains well and retains some moisture will be fine.
I usually use the finer particles that are left over from mixing my general purpose soil. When I say fine keep in mind that this is relative, my 'fines' are coarser than conventional potting soil, more like coarse grit really with obvious particles, nothing that resembles commercial potting soil.
Perlite would be a good component to start with. Some chopped, long fibered Sphagnum Moss (not finely milled Peat Moss) can be included. Perhaps what is sometimes called cactus mix can be included as well, I would not use this as true 'bonsai soil' as the particle size will likely be a little on the small side, but for seeds, not bad. In short, don't get hung up on special bonsai soils this early, it's not necessary.
BTW, in the future please confine like concerns to one thread. Doing so will help create a better experience for everyone here, yourself included. And it would not hurt to read over ynot's thread on [url=https://www.helpfulgardener.com/forum/viewtopic.php?t=3422]bonsai soil[/url] making sure to follow the links.