I will not suggest you do this for a number of reasons. First of all, if your application is sent out last week, most likely they still have not gotten to your file. If you send your supp. fee, there would not be a file to cross-reference it with at this moment.
Second, many of the schools require essays, other information, in addition to your processing fee. I will suggest that you wait till the schools request you to send a processing fee. For instance, with UCSF, not all students get secondaries. If you send a supp. fee there with no request, I really have no clue what will happen, other than taking your money for no reason. With Loma Linda, they immediately decline students without even requesting supp. fee. Again, waiting is best, if you cant, contact your schools and ask what appropriate steps you should take.