I definitely don't have all the answers on this but I can share my experience with trying to solve this exact problem myself.
My high level response is you can probably continue to do the estimates and scheduling yourself but just need an office person or someone to handle initial intake/ back end tasks. Since it's just you, I can imagine there are probably a lot of low value tasks you are doing you could hand off to either a higher priced virtual assistant based in another country or someone in the states (either locally or virtually in another lower wage state).
A good rule of thumb is to work your way up the wage ladder with hiring. Meaning, lower wage stuff gets hired out first. This would be the person on the phones, putting requests in and doing lower $$ amount quotes. They could also invoice, help put job costs in and work with you to refine your work flow. Managing the jobs and estimates is a lot more important. And the person who manages that stuff will want more money too.
3 people is not that many people to manage in my opinion. I think it's reasonable as an owner to manage up to 5 jobs at once with admin support, with all the other stuff you need to be doing. Once you get past that, you can elevate someone from your team. I saw you also mentioned finance. You SHOULD NOT be doing your own bookkeeping btw. If you haven't already, hire one asap. Depending on your size you'll pay $300-$1000 per month and you can just analyze the numbers, not input them. That's a huge waste of time.
Going through this problem right now as we speak, I wish I would have JUST had the awesome admin person, refined that work flow then start slow rolling a manager hire from someone internally. Manage your own jobs and estimate, spend more time on the phone than driving to properties so you aren't always in your car, and hire out the low wage tasks.
