You should reason with these types of clients in situations like this.
Instead of giving a single time-frame from start to finish, explain to them that you can have a somewhat production-ready tool in a span of one month.
If you explain to them (using like a piece of paper) the algorithm or steps involved in producing a software product, this will make them understand what software development is. Knowing how people generally may be towards this, you need to highlight the important parts of the production process.
For example:
- Explaining how design requires some time to plan, to ensure that the site is both beautiful and drives more sales/leads for the client
- Explain the aspect of security, as this will matter to site-users, so clients should ensure that their sites are secure (in situations where this is needed)
- Explain about SEO, etc.
I don't think you should charge a fee for explaining this process, unless you can get it done within the allotted time that they're paying for.
The justgist of what I'm trying to say is that you need to explain to clients in a way that they can see benefits directly to themselves.
If I ran (for example) a shoe retailing business, the things I'd like to hear most from a software developer is how their work will benefit my business, which is what you need to do.
You can lastly, also explain to them why it is impossible to achieve a good final product in a span of one month.
Then let them decide if, based on all the facts you've given, if it is worth itacceptable to have a half-baked product in one month instead of a better solution in a little longer time (also, 6 months is a very long time, you. You should think of trying to reduce this time to a maximum of 2-3 months. Unless, unless you deliver a rolling-product in which a working version is available soon, but you keep updating it until it is production-ready).