Hi, I Ve Been Advised Betnesol Injection 12mg At My

hi, I ve been advised betnesol injection 12mg at my 30th week of pregnancy. I had taken the first dose, but by mistake it has been taken in an interval of 3hrs i;e 4mg at 12 noon and 8mg at 3:30 pm. now when shud i take my second dose as it has prescribed to take it at an interval of 24 hr. this is my second delivery. first was my cesarian section. I am 32 and height is 5' 4". I ve a baby boy who is 4 now. Also currently i am affected with carpel tunnel syndrome.
kindly suggest the second dosage timing asap

Charu