Much of the advice about this lifestyle assumes you already have a partner. If you do not, the first practical step is finding one who shares or warmly accepts this desire. It is entirely possible, and it starts before you ever message anyone.
The work that is already yours
The deepest work, understanding your desire and making peace with it, requires no partner at all, and doing it while single is an advantage. A person who has quietly accepted their own desire shows up in dating calm, clear, and unashamed, which changes everything. That calm is genuinely attractive, and it filters powerfully for the right people. So the first assignment is not to find anyone. It is to stop treating your desire as a shameful secret and start treating it as an ordinary part of who you are.
Where to look, and how to disclose
Spaces built for open and non-monogamous people, online and in person, are the most efficient place to start, because everyone there has already opted into this kind of connection. You can also date more broadly and raise the subject once real trust has formed. There is no perfect moment to disclose, but the wise path runs between too early, which overwhelms, and too late, which builds something serious on concealment. Share it, calmly, as a genuine part of yourself rather than a confession or a demand, and treat the other person's reaction as valuable information either way.
Do not settle
Finding the right person takes time, and loneliness tempts people to settle, either for someone who cannot truly accept this or for someone who accepts it but is wrong in every other way. Both tend to end in more pain than the waiting would have. A partner who cannot accept a core part of you is not the right long-term partner, however much else is good. Hold out for a genuine fit, and search from a full life rather than from scarcity.