Plant smell

How long on average does it take for the plant to start to smell? And do some not smell or whats the deal with that?

All plants are different, and smell is determined by genetics...But generally as a rule of thumb, plants don't smell very strong while vegging, but when you flower they begin to increase in intensity. And yes, some plants don't smell much at all, while some plants will make your neighbors sleep with their windows closed cause they reek so bad.

All plants will smell eventually, early in veg they smell like any other plant without smelling like bud. Usually just before or around floweing is when you start to get the "oh shit, someones growing" smell.

im just starting week 3 12/12 from seed and theres still not 1 hint of smell coming from it

As the topic is smell are the principles the same for dried/cured bud?
Ive had some that i could smell even when its in a sealed plastic tube and others it was hard to tell if the bag was open or not.