I was the first hire for two different US multinational companies in Ireland. One went amazingly well. One was an absolute disaster. Here is some of the things I learned.
What to do
Hire a manager(me) and let them source the first few hires. It does not have to be from their network. Let them use local recruiters if need be. Do not hire the entire team or teams in one day of recruitment.
Only hire one manager, do not hire another for redundancy. They will end up in disagreement, and a small office is not an excellent place for conflict.
If the manager thinks a team member is not working out, ensure they have a full carte blanch to let that person go, do not drag it out for months and months. It damages a team like you would not believe.
Ensure you understand the local law and local culture if your new office is in another country. Do not ask the manager to set all contracts to the maximum amount of hours allowable by law. In Ireland, this is 48.
Those first few hires should have a similar outlook. Do not hire a Java engineer who only wants to do Java or a functional programming nerd who only wants Scala because all other languages are inferior. Hire engineers that want to create software and let them create software.
Give the new team a mission and metrics for success. Try to minimise collaboration if the offices are more than 8 hours apart. It drains a team if they have to collaborate in the parent company timezone, and you will have to work the parent company timezones
Once a team has a mission and metrics, Give engineers control over their tech stack. Ensure they don’t have to wait overnight for a ticket to be done by headquarters. Please give them the admin access they need to do it themselves.
Once there are a few initial hires on board, they have a mission, metrics, admin rights. Ensure that you seed a few engineers for your head office in the team. They will learn about the company culture and share any tribal knowledge between folk.
Please do not treat them like an outsourcing location. They are part of your company. Give them the exact work you would to any team that exists in your head office?
Opening a new office for a company is like doing a mini startup. It is a great a rewarding experience and I would recommend it. You learn loads, about people, about running a mini business.