What are some realistic expectations for local SEO service

So I have a local home service business. Have a website, have used some freelance SEO people to help build basics but am considering making a bigger commitment to focus more on it. It is a 7x more investment monthly compared to doing it myself and with freelancers. I'm struggling to make that commitment without knowing the return. I know SEO isn't fast but what is the timeline I can expect to move from page 2-4 to top of page 1 (locally)? And what have others seen for lead volume in that position. Traffic is great but leads are what drive business. If I can't get organic spend to be at least on par with lead generating spend from a cost per lead perspective, how can I justify that spend? Open to be educated and thanks for reading!