It's best to make a test print to establish the exposure settings as well as for contrast. You could try the test prints on 8x10 paper but the "final" test prints once you establish the exposure and contrast should be on 16x20 because the entire image won't be seen on the smaller paper. The 16x20 tests should be fully processed and dry and viewed under appropriate lighting so that you can see what the dry down effect is plus other modifications you might want to make. Often the larger print will take different handling than small ones. So be sure it is one that you want to spend the time with.