GRE general test is prerequisite not subject test. You can easily get fellowships if you have 1200+ in general test (1100+ for some state schools) but you won't even be accepted in many schools if you don't have general test scores and have subject test scores. Most schools won't even accept you for Phd program if they are not able to offer you any type of funding. complete your general test and don't worry about subject tests now unless you are applying to Ivy League or similar schools.