There is no hard and fast rule because communities vary so wildly: activity level, age of the community, number of participants, degree of controversial content, et al.
All that said, if just starting out: go slow. You’re the first admin. From there find a good, trusted, level-headed moderator to help as need be. Train him or her well and be on top of their activities early on, because moderation can really make or break a community.
From there, professionalize: get standard procedures and training in place. Communicate regularly, effectively, and empathetically with your mod team. Have good coverage of time zones when you have active posters. Handle problems as they arise and accept the fact you can’t make everyone happy. Above all else, make sure moderation is for the betterment of the community, whatever form that takes. 