1. If there is a strong competitor, paid search to get early partners with clear pain, but not willing o pay for the established competitor and lacking some features.
2. Starting SEO and Content should be Day 1. Hire a good agency or internal marketer. Survey Sparrow is a great case study here
3. Linkedin Ads - > Not for now.
4. I would also recommend picking website visitor identification software, to generate more leads and founder/sales team reach outs.