Great work! Are you going to publish on CreateSpace? I remember seeing a YouTube tutorial on adult coloring books, and how easy it is to publish on Amazon using CreateSpace. They are very popular right now, so the sooner you can get some finished pieces together for a collection, the better.
I agree with your friend--if you're good at this--strike while the iron is HOT!
Best Wishes!
Thank you so much for your kind words. And thank you for the idea, I was thinking on publishing on Amazon and a few other places. I will make sure to check out CreateSpace! :)