30 isnt bad i dont think, ideal really.
I had 20 with my daughter and found we were sometimes cutting it close so i am going for at least 25 newborn fitting ones this time. I wouldnt tho have 25 newborn only ones, they can grow out of them by 4wks so it can be expensive or difficult selling on etc so early. I'm doing the same this time that we did last time and making half of them (well,10) a nippa fastening fitted so it will grow with baby and fit for a lot longer.
I have... 21 newborn fitting so far and 8 smalls with another 3 on order and will def be buying more once we know the gender