You’ll probably hire your first manager when your team reaches 5-8 people. It’s at this level that communication starts to breakdown with too many direct communication lines and you may run out of time to train more junior members of the team
As a rule of thumb, if you’re spending more than 1/3 of your time managing your team, answering questions, reviewing work, chasing updates, or managing issues then you would be better off employing a manager. Whilst you will have to cover an additional salary you will also free up your valuable time. It will also mean that you have the right person in place BEFORE to accommodate further growth.
If you’re becoming the bottleneck because everything needs your approval then it may be time to find the right person to delegate to. A good manager should make 80%+ of decisions independently and you won’t need to handle questions from the rest of the team.
Your first manager should be hands on and comfortable doing the work AND managing the team. They should also be a good communicator to liaise with both the team and yourself.
You will then be freed up to move to deciding the direction of your business while your new manager will ensure that everybody on board is pulling in that same direction. As you move away from the day to day you will also have a clearer view of your business which will enable you to lead it better.