normally, the trichomes start to show around the 3rd or 4th week of flower. you could just have some slow growing plants. it also depends when you count as the first day of flower. if your buds are very small yet you probably wont see them yet. once the buds start to look like little nuggets is when the trichs start to show.. more than likely you just need some time and they will start to pack em on. from what i read aurora indica is mad loaded with trichs at the end of harvest like even covering fan leaves so i am sure you will be ok.. again probably just need to give em some more time. also, what size area is it and with what light. not enough light could also contribute to slower growth and slower trich production.. just my 2 cents there though.