Time zones is the arch rival of distributed companies (or rather, the earth being round, but I digress into the meaning of time zones).
When you run a distributed company and you hire people, you might be tempted to hire from all over the world but there’s a problem. If you hire someone that lives 12 time zones away from you, you’ll barely interact with that person and suddenly the company moves at a day-cadence, instead of immediate cadence.
The second problem is that those people in the other side of the world will develop their own culture, their own style, an us-vs-them mentality in which you, the company, is them. All unwanted traits.
My advice, when getting started, is not to hire anyone more than 4 time zones away, so, you can end up with half a day of work of overlap. Only after you have very trusted and senior managers 4 time zones away, you can hire people 8 time zones away that have 4 hour overlaps with those managers, and repeat until you have all time zones covered by trusted senior managers that can carry the culture of your company.
This means that you are unlikely to go fully global until you are at least 50 and even then that’s pushing it. I’d be uncomfortable with a fully global company that’s smaller than 200 people.