Is this your first grow? I'm thinking it is - and so welcome to the wonderful world of growing weed! One of the best things you can do for yourself (and for us!) is to start a diary so that when you have questions or run into problems, the community will have as much information as possible and will hopefully be able to offer good solutions and responses.
It seems to me you are growing an autoflower because you are seeing preflowers at week 4 - this is entirely normal and when they are expected! I've had only one autoflower wait until week 5 to go into preflower so things are going well for you!
As far as lighting is concerned, you should give 18 hours of light all the time - right up until you harvest! Photoperiods won't go into preflower without having their light changed from 18/6 to 12/12 - that's called flipping it. So ALWAYS give your autoflower 18/6 light.
As for the nutrients, you're probably not giving them all they need right now. 1/8 is great to start them off but increase that now to about 1/4 and start adding some bloom nutes as they will be needing more of the micronutrients those give the further into flower they go. You can probably start the bloom nutes at full strength right now and increase your grow nutes to 1/2. I don't know what nutes you're using so this is just a guess but from the picture, I think she definitely needs just a little bit more nitrogen. The way I feed my autoflowers is to give them only water for the first 2 weeks and then start grow nutrients at about 1/4 strength in week 2, 1/2 strength in week 3, full strength week 4 and add bloom nutes then, too. From there on, I taper off the grow nutes and increase the bloom nutes.
The smell of cannabis doesn't come until there are actual flowers so you've got a little time left until you'll start smelling it - and the smell will most likely be weak at the beginning. The smell gets stronger as you get closer to harvest. Some strains don't smell very much ANY time but yours definitely will... just give it time!
I hope this has helped a little bit - but will encourage you to start a diary so we can help you with more accurate advice if you have other questions in the future! It will, as I said, help US help YOU!
Good luck!