回复：关于J1的急问,周一前必须答复,多谢各位了!!!

My experience:
1,I don't know if you need to be outside to change your status from F1 to J1, maybe not, but you have to show you have enough money for a year to be a J1.
2, Without waiver,you have to be outside US to change status from J1 to F1, it is a big risk now.Furthermore you have to be waiver from now on once you have been a J1.