The amount of time that CBD takes to have an effect all depends on the user themselves, the CBD product and strength they are using, their symptoms and how they are consuming CBD. Don't go into using CBD expecting to get a high out of it- mainstream CBD products contain very minimal amounts of THC!
One of the ways of consuming CBD to get the fastest acting benefit from it is to vape it, which can provide near instant results. Oral consumption via tinctures or sprays can also provide very fast results, with the effects becoming noticeable within half an hour to an hour, and longer lasting results.
If you don't get results straight away after first using CBD, it's worth persisting with it for a while, as some users have reported that they haven't gotten any results from it for days or even weeks, but once they did it had become very effective. If you find CBD isn't working how you expected it to, you should consider increasing the strength of your CBD product or the method in which you are consuming it.
That being said, CBD works differently for everyone, and what works for one person may not work for the next, or in some cases it may not work at all. It's well worth taking your time to see what works best for you, trying out different products, strengths and methods of consuming CBD!