baby's kick

hi, im in my 18th week. is it normal if the baby does not kick after 3 days of kicking. still waiting for my baby to kick, or i just don't realize it while working? there's a day my baby only kick at night when i lay down, then there's a day when the kicking happen in the morning only. now, I'm worried. i wanna do detailed scan but the doctor said need to wait till 19th week. what should i do.