The time of harvest and way the cannabis is grown do have an effect on CBD levels, and indicas tend to favour higher (note: higher, not 'high') CBD levels... but unless the strain you are growing has special high CBD genetics it's very unlikely you will get a strain with more than 4% CBD, which is what is considered 'CBD rich'. Examples of such strains would be those from CBD Crew, and stuff like Cannatonic, Harlequin, Sour Tsunami. So yeah you can increase the CBD in your crop by controlling harvest time, grow type, choosing indica, but it's unlikely you'll get enough CBD to actually feel the real benefits of it when consumed. It needs to be in the genetics.