Files are burned in the alpha-numeric order: those that begin with special chars first, numbers second then letters. The sure-fire way to have your files sorted properly is by prefixing then with numbers, viz:
Be advised, though: if your filenames are long enough, the order in which they are burned may be not what you expect/see in Nero or Windoze Explorer. That's because you see them in Joliet format, but the way they are burned is sorted according to ISO9996. With very long filenames it is hard to predict if the ISO9996 filename sorting will mirror that of Joliet; so your best bet is to keep the filenames short and sweet (32 chars or less).
To avoid wasting media, try burning to an image file (NRG or ISO) first. Then load it into ISObuster and sort the files by LBA. That's the order they wiil be burned in on a disc.