A big decision on the niche

Dear The Life Coach School, I am thinking of quitting my job in 2021 and start my coaching business. I am currently learning how to set up my website, and start my podcast this year, in prep for my business next year. While I am still at work this year, I thought of doing free coaching to get practice. what do you think about it? and also I decided that my niche is humanitarian workers in their early careers who find themselves complain a lot. and I would like to help them reduce this complaint. Do you think it is a specific enough niche or do I need to narrow it even further? thank you for your feedback.