The best age for becoming an entrepreneur is your current age. I co-founded https://www.roninapp.com back in high school. We then started https://www.reamaze.com after grad school. And we just launched https://www.clearalias.com a few months ago. Doesn't matter what age you are. It's all about opportunities, timing, and the people you get to work with.
I was talking to someone else on Facebook that complained about the same treatment from Groove. They change pricing and don't let people know. They also don't do grandfathering which is ridiculous. I've recommended they go with Reamaze (https://www.reamaze.com). Much better product. Awesome team. Fully transparent and great communications / service.