Start with writing down your ideas, your minimum requirements and what budget you have in mind. You may have some ideas about how you want it to look like. Take photos, download pictures, all these things help me understand what you are looking for.
I don't charge for an initial consultation in the Hawke's Bay area. Let's talk if you want to use my services and you live in another region as I may be able to make it work!
I can certainly draw up your own design or the design of another professional (as long as there are no copyrights on this) and I don't foresee any problems that can't be resolved. I may make some suggestions during the concept phase (e.g. if there is a more (cost) effective solution or the proposed design will cause challenges down the track), but I will of course discuss these first!
The design can take from 2-3 weeks for a small alteration to 4-6 weeks for a larger project. In addition you'll need to allow 20 working days for the building consent process (longer if they have questions). Some projects require input from other professionals such as engineers, so you will be reliant on their availability and timing. I can give you a time estimate once I have an idea of what you want to achieve and what is involved.