I suggest working with a group for a few more years. If you want to go it solo, consider creating a LLC and moonlighting for other clients. You may not notice it in residential, however, in commercial large firms compete for talent and hire away appraisers from each other. I think that might start happening in residential as well.
The key to a successful residential lending business is know when to take projects and when not to and how to find customers and manage your time. Right now you have someone doing that analysis and they are ensuring projects fit your wheelhouse. The appraisal market you are seeing today, is NOT normal. As a residential lending appraiser; when things are normal, you have to decide on if you want the client to look at other appraisers if you turn down work.
You also need to learn to find work and always be adding clients, clients will come and go, however, you will need to keep making a living.
BAD IDEA; Hiring members of your household full time:
As a risk analysis, it is a terrible idea to hire anyone in your immediate household full-time. Both your careers are tied into the same very niche industry. If you are a solo practitioner, you are paying for both your healthcare, retirements and social security. If your spouse was at a company, the company would be adding an on and off-tax return income of $8,000-$20,000+ to your household through providing non-taxed and tax-deferred benefits to your spouse/partner and you by the domestic partnership. Additionally, experience as assistant to the president of a one-person appraisal shop is significantly less salary and has much less career potential than an assistant to an executive of any corporation. If your partner goes through a career change and can add value, great, but full time, it is a bad idea. In particular because all professions can be done remotely, they can still work from your home while receiving a salary and benefits from a corporation. If you have an injury, or any professional licensing problem, you both will be out of work. If you want to get them licensed, consider them helping you part-time. For full-time help: Hire anyone other than people in your household.
If you seek to have a business setup and do not have the skills, you can hire consultants to guide you. The cost is only $5,000-20,000 depending on how much help you need. If you like the practice of another appraiser, just hire them to get you up and running.