Throughout the life cycle of a MJ plant the smell gradually becomes stronger.
smell really wont be a issue in first grows and early veg. but will be in flower.
but alot of the time it really just depends on the strain
some stink way more then others.
but you might as well be prepared and over-design your air filtration system it will only a) increase the yield and b) prepare you for flowering.
oh how i dream of the strain that has no smell
.