With rent subject to change... what if you start the "non-smoker" out at a lower rent rate and they turn out to be a "smoker" or take up smoking later?

We don't allow pets, smokers or more than 4 people in the house. 

I think renting to a former manager is kind of like dealing with a former smoker.  

I recently found out he is a smoker.

Smokers please do not apply.WHAT IS WRONG WITH THIS AD?

Our prelim scoring is based on objective non-discriminatory items, such as if they are smokers, if they have lived in the area (have roots), have held job for over a year, income, how long they have stayed at previous addresses, how long they intend to stay, Facebook/google search, unverified look at criminal, bankruptcy, evictions, bank accounts.  

I don't know what California's laws are, but I would think you are safe to do as you please, its no different than not allowing smokers. 

Smokers, lawyers... 

So we accepted this person ( single person, good income, good credit, no pets and non smoker). even though the move-in date is 5/1st.

You just can't deny them simply because they belong to a few protected classes.But, that doesn't mean that just because they are in a protected class, that they also can be a smoker or show up late, blah blah.You also have rights as a landlord.