For your home buying example, maybe there are services that you can offer related to home ownership (e.g. subscription based handyman or gardeners), so that you can be top of mind month after month, not just once a decade when people buy houses. You can then be a great resource when people go to buy a new house as well.
Your users are somewhere along the spectrum of: Unaware <-> Problem Aware <-> Solution Aware <-> Product Aware <-> Most Aware
Where they fall on that spectrum will determine how you interact with them. Try researching "problem awareness" or "customer awareness".
- Figure out how to target the people who are immediately looking for your service or might be. For the home example, people going to open houses, people searching mortgage rates, renters who just had a kid or got married, Employees of a startup that just IPO'd or was acquired.
- Try to get referrals from happy past customers. I've used home buying services and also recruiting services that will just straight up mail me a check for thousands of dollars if I was a customer, and sent them a friends referral.