Help, when do you think i would go on en pointe? thanks x?

Well, i really want to be on pointe i know i have to wait.. i would rather wait then mess my ankles up..but i was wondering what point you think i could go on? i Started ballet when i was 11.. and i am now 13 and am a solid grade 3 dancer(im english) i dont know if the grades are different for USA. but how old do you tink i will be by the time i get to demi pointe and en pointe? xxx thanks xxx